RE: Cutouts - fact or fashion
I'm not sure that simulation testing is less expensive than prototype testing, however, I can't solidly validate this opinion one way versus the another. Yet my thought is that prototype testing is probably the most versatile, and ultimately less costly, especially if a number of candidate designs or versions being experimented with is numerous. What it really comes down to is the number of focus concerns. In reality, I think a practiced tester is better positioned to discern the range of performance in a practical way to the designer, particularly if varied testers are used.
Regarding erling's comments, I have to think that cutouts aren't targeting an irregularly shaped planing surface, as most designs are clearly balanced off the centerline. Of course, the actual shape of the wetted area can be viewed as irregular shaped when considered solely off centerline, but the sum of both is balanced overall. No asymmetrical concepts in today's offerings. Nonetheless, I have to think that overall lift is affected by cutouts. Similarly, I would think that overall range of performance is crucial to an optimum result, so cutout concepts must be efficient and productive across a broad range from light to strong wind conditions.