I just got the Simmons DA200S today, so I can't speak for its reliability yet.
I did a fair amount of research, starting from scratch and looked at most of the options.
I was concerned about the Simmons brand name quality before I started reading all the reviews on this unit.
I was in the stores a lot recently trying out every imaginable kind of amp - LOL
Settled on the Simmons. I'm sure there are other e-drum amps that sound better, if you're willing to pay a lot
more. But this one hits the sweet spot - for both price and sound. All frequency ranges that drums, cymbals, and percussion instruments are capable of producing, are pretty faithfully reproduced. It's got 5 speakers in it with the amp putting out 100 watts to a 12" down-firing woofer (that really works - it puts out bottom end whoop-ass), and 50 watts each going to a pair of 6.5" mid range speakers, and a pair of 2.5" tweeters.
I also tried running a bass guitar and keyboards through it (at separate times). It's just awesome on the bass compared to the crappy little practice amp I've been using. And it sounds better to me than most of the dedicated combo bass amps I've tried. Must be the extra speakers giving it a bit more shine.
Keyboards need to be dialed in with eq a bit, as they can get overly bass-heavy with certain sounds.
It's a tad bit heavy if you'd be lugging it around all the time. But its got a lot of good stuff in there. Sounds excellent. And if it holds up in the long run, I'm sure I'll be very happy with it.
Details here: http://www.simmonsdrums.net/da200/