Any thoughts or recommendations regarding the Emotiva SE8 or REL subwoofer?

Rel  would be my choice. You might want to check out SVS.Their newer models have DSP included that you can use from a free phone app at your listening seat.

If your looking for subtle or extreme bass support to your taste where and when you want it, any rear panel manually controlled set it and forget it subwoofer is going to be frustrating. 

I have a remote controlled subwoofer system with six memory equalized presets and I'm constantly changing the gain, EQ, or simply turning them off all at the touch of a button from my listening position. 

I believe SVS offers similar functionality along with a free trial period?

After a direct in home comparison I can not recommend REL.

My short lived Emotiva amplifier went up in a little puff of smoke in the first few weeks. No experience with the SE8. Have fun with your search. 

I am not a bass freak, and would be more concerned about integration and overall balance.

First, and most importantly, get two subs for music, not one. If it’s me, SVS has dual SB1000 subs at a discount under $1000 with a truly risk-free (including shipping both ways). If your budget is higher I’d look at JL Labs, Rhythmic, or Rel, whichever you think better matches your needs. But, dual SB1000s at that price with a software integration app included and a risk-free trial would be tough to pass up, and they offer small size and true 20Hz depth. If they don’t completely rock your world, just send them back and you’re out zero dollars, but I strongly doubt you will.  Hard deal to pass up IMHO unless you’ve got lots more $$$ to throw at this.  FWIW, and best of luck.