REL S510 or S812


Hello all

Im buying a new sub. Ive narrowed my search down to REL. My budget is enough for a new S510 or used S812. My system is dual purpose so Sub has to be good at HT and 2 channel. Thats why ive landed on REL. Im not a fan of buying used because of warranty consideration mainly, but if the 812 is  considerably better than the 510 I would consider.  Does anyone have first hand experience with these subs?  

sandrodg73