SVS vs REL and experiences with both: your comments and preferences...

I want to make a point on value here. Obviously the SVS has better value per say but considering the Euro dollar, anyone within the US. and especially Canada(like me) get slaughtered on exchange and duties. Hence the value difference. But I can still say, fit and finish, engineering is phenomenal on the Rel’s. The SVS to me is just okay.....

Also: from a “Musical” term used frequently in this hobby, I find Rel to be far more musical. The SVS has the boom trophy. 

I’ve had 2 SVS woofers, one dead right out of the box. SVS customer service was great, but woofer number two had a dead amp. Complete garbage IMO. Bad luck, sure... but, come on man! My S510 is great. No complaints, yet.

I currently use 2 RELs from the "Q" era, a Q108MKII and a Q150e, and both work perfectly in my main hifi rig...can't recommend them more highly, and they cost 200 bucks each (pre-owned) at different times around 5 or so years ago...had the 150e first and loved it, so when I found a clean 108 (a friend has 2 of these) I added it...great move as they sound excellent together. 

I have not owned any current Rel but I do have 2 x SVS Ultra SB. My buddy had the Rel G1's and after hearing my two SVS subs, he just sold his 6 x G1 subwoofers. I'm not a big subwoofer guy and I don't utilize them to their maximum but instead only look for that last octave. However I do like articulated bass and I find after owning many different subwoofers that the SVS Ultra SB does everything correctly and nothing wrong. Highly recommend!

I have two RELT9i integrated perfectly with Harbeth speakers.  They sound right with music, plenty of deep bass and punch when the music calls for it- never overbearing or blocking any midrange detail.  No slow or lagging beats- they keep right up with the mains. 
These are the first subwoofers to accomplish this out of others I have tried. 
I have no interest in any other subwoofers.