all my bikes have coaster brakes on them, and they're all good quality, like Shimano, Bendix, Suntour, and Sachs.
KT's, HiStops, YCC's, and other cheap brands fail all the time, even on bikes without motors. (i'm not gonna argue this with the walmart crowd, i've seen it happen, and it's well documented on this forum, as well as walmart's own site in the reviews...)
i also use front drum brakes, mostly 'cause i like the old-timey look.
i was thinking about the brake question the other day, after someone was trying to convince me to get discs.
people will tell you what brakes they think are best, usually claiming discs are, but my coaster brake will lock up the rear tire as fast as a disc can, and my front drum will lock up the front wheel, also.
braking only works as long as a wheel is rolling. once it's skidding, you lose traction.
so, you need a brake that can slow the wheel down rapidly, without sending you into a skid.
no matter what brakes you use, if they do that, they're good.
on that note, it's gotta be a quality system. if your brakes break, you won't stop. so whether you get discs, drums, rim or coasters, they gotta be good quality.
with a coaster brake, you should definitely have a front brake also, no matter what kind of hub you're using, 'cause if you break your chain, you're screwed.