Broadway auds and producers often swoon over Brit productions so, as gambles go, trans-Atlantic transfers of prestige projects would seem to be a solid bet. And, of course, it’s always cheaper to remount an existing production, right?Maybe not, thanks to a tangle of fiscal considerations that make it far costlier to mount and sustain a production on Broadway than in London. In some cases, producers have to frame a Broadway run at least twice as long as the London one to even hope for recoupment. This season, like many others before it, is chock-full of London imports, with plays “Red” and “Enron” and tuner “La Cage aux Folles” joining the still-running “God of Carnage” and the strong-selling “A Little Night Music” revival. But while there are advantages to shifting acclaimed productions across the Pond, it’s far from a surefire strategy. For every hit like “The History Boys” there are undersellers like “The Norman Conquests” or outright flops like “Coram Boy.” Consider “Hamlet,” the Jude Law starrer that moved rapidly from the West End to the Rialto last fall. The $2.5 mil transfer proved a success, but margins were tight in a limited 12-week run. Most of the company came over from Blighty, so rehearsal expenses weren’t as high as for a new cast. But the show’s producers, led by Arielle Tepper Madover, still had to pay housing and per diem for those out-of-towners for the duration of the run. The Actors’ Equity minimum for per diem is $71 plus single occupancy housing, but star thesps are accustomed to more — with weekly per-diem costs sometimes adding up to $1,000 and monthly housing hitting $4,000 or $8,000 for prime Manhattan digs. Such costs, of course, mitigate the gains that come with a transfer. “It’s really hard to tell if you’re saving anything,” says Madover, who’s also the lead producer on “Red,” the upcoming Mark Rothko biodrama starring Alfred Molina. Next season already has its share of Pond jumpers — London’s National Theater smash “War Horse”; a revival of “La Bete” starring David Hyde Pierce, Joanna Lumley and Mark Rylance; and a move of Jez Butterworth’s kudos-magnet play “Jerusalem,” also starring Rylance — and producers continue to refine their checklists of what makes for a successful trip. The first decision, of course, is whether something deserves a transfer — and in that, money concerns rarely play a major part. “The starting point is, ‘Why are we bringing this to New York, and what are we bringing?’?” says Sonia Friedman, whose trans-Atlantic output includes “Boeing-Boeing” and “The Norman Conquests” as well as “La Cage,” “La Bete” and “Jerusalem.” “You don’t even think about the finances at that point.” “So much of it based on your gut,” says Bob Boyett, the American producer (“The History Boys,” “The Seafarer”) who is helping shepherd “War Horse” to New York in what will be a co-production between the National and Lincoln Center Theater, presented in association with Boyett. “There are some plays that are so dear to you that you want to do them even if there’s a good chance you won’t make any money on them.” Boyett and Madover have struck what are essentially first-look deals with Brit troupes. In exchange for contributing coin to a theater’s overall budget, the producers get first dibs on offerings from the National and the Menier Chocolate Factory (in Boyett’s case) or from the Donmar Warehouse (in the case of Madover, whose Donmar transfers include not only “Hamlet” and “Red” but also “Frost/Nixon” and “Mary Stuart”). The next step is determining what elements of the production drive the transfer. In some instances, keeping the Brit cast intact has creative importance, as when a playwright has written roles for particular thesps. In others, it’s more feasible to bring over a handful of actors whose performances galvanize a production, then surround them with American faces. Friedman has taken that route with “La Cage,” which features Olivier winner Douglas Hodge, reprising the role he played in the hit Chocolate Factory staging and its West End transfer. He appears alongside a slew of Yanks, including Kelsey Grammer, whose participation helped make the show seem a viable draw Stateside. Coming into New York fast on the heels of Brit success is often preferable, particularly if it’s desirable to bring over a large chunk of cast. The cut in rehearsal time not only reduces costs but also more likely fits into the hectic schedules of the busy Pond-hopping directors — such as Michael Grandage and Nicholas Hytner — who often helm such outings. There are the usual concerns about available Broadway theaters, an issue that’s become increasingly thorny as recent seasons have filled up quickly. One major advantage of presenting “War Horse” at LCT, Boyett says, is that the expansive stage at its Vivian Beaumont Theater seems the best fit for the big, puppet-heavy epic. Any legiter will tell you everything costs more on Broadway than in London, due to a variety of factors including U.S. labor minimums, which are higher. So if a producer is figuring out how long it will take a limited run of a play to make recoupment viable, the rule of thumb is: longer than in London. Friedman says she tends to double the week count. Hence, “Bete” will play nine weeks in the West End but 20 on the Rialto. Selling a London import is usually aided by strong critical reaction in the Brit press — which almost always plays a part in deciding to transfer something. Sometimes a show can get a boost from a thumbs-up by New York Times critics, who periodically travel to London to give their take on the scene there. Brit praise, however, will only carry you so far. “It’s very useful to the 30% or 40% of theatergoers who are knowledgeable enough to know, for instance, what an Olivier is,” Boyett says. Still, commercial rewards of a hit on Broadway are often more substantial than those of a London success, thanks in part to higher ticket prices and, in the case of a smash, intense demand for premium seats. Friedman’s experiment with “La Bete,” the David Hirson comedy inspired by Moliere, rolls the West End and Broadway capitalization into a single global budget. Upfront, that will likely add up to about 1 1/2 times the average cost of mounting a play in Gotham (which often hovers around $2.5 million). The lead actors will star in the show on both sides of the Atlantic, but the West End ensemble will be British while Broadway’s will be American. According to Friedman, it was a commercial decision. “It’ll be fascinating to see if all this saves us any money,” she says.