Well you could definitely be using a worse subwoofer for sure, but it’s still the first piece of equipment I would change in your setup. How big is the room? My hunch is that there’s an integration “thing” going on, but part of it could be room size. Sunfires are ok, but won’t punch you through the back of your seat. The midbass/bass weakness your describing could be due to being on concrete, and/or a large room. It could be a XO null too. The only way to know for sure is to measure the FR, or at least use an spl meter and change XO points, or add distance to the sub in the AVR.
I say new sub, and better integration.