This. Most class D amp heads use power modules from Hypex, IcePower, Pascal and similar. The modules are readily available, proven, reliable designs and it simply isn't worth amp makers designing their own/reinventing the wheel.
Most modules are at or around two power ratings - either 300w into 8 ohms/500w into 4 ohms or 500w into 8 ohms/700w into 4 ohms. Some amp brands inflate their power claims. I have a Carvin that claims 1000w, but it's no louder than my 700w Aguilar if you turn both up to the point that the clip light flashes. I wouldn't be surprised in the Peavey mentioned is the same.
Watts are cheap nowadays. All amps have a volume control, so unless funds are really tight, buy the more powerful version, be sensible with the volume control and don't over-drive your speakers (you'll know when you do because they will make horrible noises). Your sound will benefit from the additional headroom and when/if the time comes to up the size of your rig, the amp will still be up to the job, saving you from having to sell and upgrade it (which always costs).