i tried the hartke a25 before and was very unimpressed. there is a general belief that bass amps, below a certain size and wattage, just don't cut it. a bass amp needs to push air to get the lows, period. you can forget about those 10W 8" combos. frankly, you'd do well to forget the a25 as well. go for the a35 at least.
i haven't had experiences with the hydrive but i've tried the metal cone models. at loud volumes, they start to sound very thin for my liking. if you had 8 10s pushing a wall of air i guess it may be compensated, but that's just how i rate the metal cones.
hartke has a new line of paper cone amps. check out the samsontech site.
peavey makes loud amps.