The old PowerTap hubs may have pretty lame dimensions, but they're almost the same as a DT240 (which again is pretty poor). Many people have perfectly functioning rear wheels using that hub so why do people have so many issues using a PowerTap? I don't get it?
It depends on wheel build and riding style. Flange dimensions are only one factor in wheel lateral stiffness. Wheels with more spokes or stiffer larger cross section rims will be stiffer no matter the flange spacing.
Riding style has a lot to do with whether a given stiffness of rear wheel is enough. Some people ride in a way that puts more lateral force into the rear wheel. Either when sprinting out of the saddle or climbing out of the saddle. For example I'm a skinny 145 lb climber who doesn't make much power but I break a lot of rear wheel spokes. It's because I do a lot of climbing, climb out of the saddle often, and rock the bike side to side when I do. I've tried keeping the bike still and but feels weird and unnatural.
If you put enough lateral force into the wheel then the NDS spokes at the contact patch go slack momentarily. That causes them to flex and eventually break at the elbows. When I was using my old style PT wheel all the time I had to get it rebuilt every 9 months or so (about 6000 miles) after more than 2-3 spokes had broken. Its been rebuilt six times. I finally started doing it myself, then got crank based PMs so I could spread the load across more wheels (and also could build stronger wheels).
It's not recommended by Saris but you can lace the older PT hubs 1x heads in on the DS. I do that on BHS hubs and the PT hub's larger flange will work better with 1x heads in than smaller flanges do. It increases the effective DS bracing angle by a significant amount.