Has anyone here had any dealings with Tekton, particularly their subwoofers

It all depends on your expectations and how high your bar is. I briefly owned the original Pendragons a few years ago and recently had a chance to spend a weekend with the Double Impacts. If you want a speaker that can fill a room with sound effortlessly at a relatively inexpensive price, look no further. But if you value imaging, a 3d soundstage and refinement, there are better choices. 
 

No free lunch or giant killers here. For my taste they are only “ok”, but not nearly as bad as some here would lead you to believe.

Not sure how those Double Impacts were set up, but in my dedicated audio room I have fantastic imaging and they float a very large and accurate soundstage.  They exceeded the Magnepans I had at the time which were quickly sold once the DI's were dialed in.

I must say that the ulfberht are fantastic you can have them in beryllium ceramic or normal but they are big in size.read the review done by stero times. Enjoy the search and the music.

That’s funny because we put some Magnepan LRS speakers in directly after the tektons and both felt that bass and dynamics notwithstanding, the Maggies were the better speaker. I’m not slamming the DIs, they were competent at everything, just not great.

I've bought from Tekton three times, The Perfect SET, Impact Monitors and some kind of center channel his was selling in ready to ship.   Two of the transactions went fine.  The Impact Monitor transaction did not.  Ordered them with grills.  The speakers showed up and the grills did not.  It took weeks to get the grills and when they arrived they didn't fit, too short by a fraction of an inch.   Let Tekton know and they said they would ship replacements.  After bugging them monthly for about 6 months and no replacements ever shipped, I just got a refund on the grills.   

So, my suggestion is to not get any Tekton speaker prepped for grills.   Eric Alexander still uses pin type grill mounts which suck.  He should have converted to magnetically mounted grills 15+ years ago like nearly every other speaker manufacturer has done.

Also, all eight feet receptacles came out of the speaker cabinets when I replaced them with higher quality GAIA feet.   Had to use glue on all eight inserts to reinstall them.  Not a good look on a pair of $3000 Impact Monitor speakers (they have bunch of factory upgrades).