I'm not a fan of the class D amps at all for subwoofers. They're high wattage for sure, but they seem to really feel more comfortable far below their max spec wattage. I dont' have anything scientific to base this on at all, unusual for me for those that know me, but I have done several a/b's in a DIY "club" (for lack of better term) where we swapped amps in and out. A 500 watt amps seemed to have much less problem delivering the juice at high than the 2 class D's we had. I think the class D topology suffers from not having beefy PSU's and large enough caps for delivering that raw current to low impedance drivers. Instantaneous power for short bursts, it can deliver a bit, but a longer bass note, or multiple bass notes and they struggle a bit. Still lots of power, and you can't fry eggs on them like the ol' class a's and b's, but they high specs are quite misleading. I could be off, but we all heard it.

That Dayton sub is an absolute workhorse - class G, a bit different from the D's, similar efficiency (does anyone really care about that though?) but a more conventional output stage.. Features aside, it's got plenty of juice.

FWIW, most people I know running one or more Tumults or whatever giant woofers you can think of tend to just buy big, high current capable pro-amps and bridge them for gobs of power. I have a 400 sq ft plus room that does more than fine with a "small" 240 watt amplifier driving my 88 dB sensitive 15" woofer.