OK, finally narrowed my choices for my system as follows. Listening Room is about 500 sq ft. Any advice on my choices?

Main Speakers: Axiom M22i
Receiver: Denon 3803 ...OR ... Pioneer Elite VSX-45TX
Sub: SVS 20-39PC-Plus ... OR ... HSU VTF-3

Thanks.

Get the Denon and the SVS as long as you don't mind having a water heater looking sub.

Denon makes better electronics than Pioneer. Denon has a far better reputation for having excellent dynamic headroom and good cooling systems than Pioneer. Even Pioneer Elite I find struggles with low ohm loads and high volumes. A 5000$ receiver shouldn't do that!

As for the SVS, at its price point it out performs anything else. However, they might not be aesthetically pleasing to you. Take a look, if it looks good to you, then buy it.

It all sounds good.
No problems anywhere there i would say.
Any of those components should do you just fine.