500 Series worked best for me. I have installed signature 1500 with good results as well. Recently I switched to Sonance though and I am happy with the choice.
Anyway, if I am restricted from purchasing Snaps signature series why not go somewhere else?
Their rewards program should be probably discussed in separate thread. I feel like being punished for not doing enough business with them by restricting an access to some of their offerings.

I'm a fan of Kef also but there's no way I can deal with those metal-plate prewire brackets.

Do you use those or have you found something else that fits the size?

I also use KEF and think they are a good value.
What is it about the metal plates you don't like? I did a job not long ago where I used something like 12 pair of them on a prewire. They look funky but I had no trouble with the sheet rock guy cutting out the proper hole (was actually worried the idiots might cut out the smaller holes too). The metal is nice and ridged compared to plastic rings.

I actually bury the wires now, take pics with measurements, and cut myself. I've had too many sheetrock cuts cut my wires or cut the outer edge of rough in rings far too many times to count. I just charge for the extra time to cut them out. I do agree about the metal brackets, I'm not a fan of them either.

Most of the testing was done with dealers we invited to headquarters, external audio experts and internal experts at the SnapAV, Control4 and Triad headquarters. We compared to many brands such as Origin, Sonance, Klipsch, etc. Additionally, Signature was debuted at CEDIA this past year and while we didn't have a blind test setup, we did have a live demo in which the feedback was outstanding. Lastly, since the product has been shipping we have heard from a number of installers who tried Episode for the first time who are extremely happy with the performance both in the field and in show rooms.

We hope you will give them a shot too!

I've never had any issues with the standard plastic "circle with wings" prewire brackets that most manufacturers use. Occasionally there are times when I need to reach through to remove the ring for one reason or another which is not happening with the those metal plates.  Sure, in a perfect world they would work just fine but I've yet to find that perfect world!

That's the way we did it way back in the day before the prewire brackets even existed.

They save so much time and mess that I use them most of the time but do bury occasionally if it's needed.

They definitely save time and the mess. We just charge to compensate for that. Got so irritating going back on almost every job and the rings got cut out wrong.