For now I'd stay with your LS50 and SVS 1000Pro combination and work to position it the best that you can. Sometimes a little digital equalization can help a lot. I have 3 sealed SVS subs & 2 RELs. Both are good. Your SVS is great for those speakers.
Sad to hear you were talked into Tekton with the most biased person out there. I've heard them plenty at shows and they never floated my boat. Seemed homemade to a very large degree, and I get nervous about 'one-of' designs that no one else has thought worthwhile to emulate. Those LS50s have been reviewed far too positively to have been discounted so easily. Sell the Tektons. Good luck!