Older vs. newer REL subs

Again, my REL subs have been in fairly constant use and haven't rattled apart at all...I've taken them apart and would notice anything rattling. 

@wolf_garcia,

The only issue I've had with my REL subs is the surround coming loose from the frame on my G2 but some heat/pressure reattached it with no issues. Of course, this driver really has some extreme excursions when played aggressively as I'm known to do from time to time!

I'm following this thread with a lot of interest. I have a T9i sub and have been contemplating whether to get another T9i (used) or save more to move up the line. The problem is that I bought the T9 in white to match the KEF LS50s which were also white. The KEFs are now gone, and the white sub doesn't go with the aesthetics of my room anymore. So the question now is whether I sell the white T9i and buy a pair of black T9is, or buy a single S/510 for now, and buy a second one next year.

I have read many posts about the S line being better, but don't quite understand how specifically. I called REL customer service and they feel that a pair of T9is are more than sufficient for my needs (not a bass head, no EDM or hard rock/metal for me). But I do wonder what will I be giving up by not getting into the S line? Hopefully, someone who has actually moved from T to S will chime in soon.

BTW, one thing I can tell you is that the T series is absolutely better than the older REL subs. I had the REL Storm III about 5-6 years ago, albeit not in the same room or even the same equipment/speakers. While it had adequate bass and pressurized the room nicely, I yearned for the bass to have more punch and texture. The T9i definitely delivers on this aspect. The bass is more focused and 'well put together' if you will. You definitely feel the improvement when listening to classic rock for example.

OP - sorry, didn't mean to hijack your thread. If this sounds like too far removed from the topic at hand, I can start a new thread :)

The best upgrade one can do for an older ST series REL is to replace the rail caps with Mundorf caps and double up the resistance wattage capacity on R7 resistor which is a known failure point on older REL's.