Rel Subwoofer questions and help

I ran all the different B-series in my system years ago.  I always liked them.  I'd keep the B3 pair you have now.  The only issue with the ST and the B series (essentially the same amp layout) is eventually the amps fail and they have to be sent off for repair.  I only know of one shop in the Chicago area that repairs them from about $300.  They had to repair my Stentor III amp and a B1 amp of mine years ago.

Adding a B1 could be a nice addition.  If it's a good deal, you could just use it as a spare if the day comes when you need your B3's repaired.

I don't have subs, I just wanted to say:

I went to NY Audio Show, I never saw so many REL subs in my life, and they all appeared substantial, well made, and in the brief listening in those rooms, added extension without revealing their location.

I started with the T/7x and the now the Sire S 850s.  My experience is that REL has come a long way in the last decade. They sound so good I cannot believe I went 30 years without subs. 

One thing that really floored me was that I could listen to full, satisfying music QUIETER with subs. Before I would push my Wilson Sasha Vs hard to get full bass bloom. Now I don’t get listening fatigue from too much volume and even better my family isn’t subject to my loud music throughout the house. 

I have 4 REL B series subs and a couple of their newer ones (different systems).  I love the deep growl of the B series, especially the B3, the smallest but I think the tightest and fastest of the line.  I'm certainly happy with the sound -  you just have to be careful to dial them in right or any sub will sound too thick.

Main concern is they are getting long in the tooth.  I don't know that buying another one used is a great idea unless you are getting a serious good deal...like I just got one for like $250.  Otherwise I would suggest just keeping the two B3s that you have, and letting them run until death, then look at some replacement. 

As @lanx0003 mentions-

"It may feel a bit rounded or thick." That MIGHT be  the result of B series ported cabinet vs modern REL passive radiator design-closer to acoustic suspension/sealed design? Settup/location might fix that.

I use 2 cherry finish REL B3’s with satisfying results. When they die(nearing 20 years), they’ll get replaced with new REL’s.

The fact you have 2 REL’s and not just a single sub is more important to SQ than be concerned about not having current models.

Location/setup is paramount.

If your B3's are cherry finish, I have a home for them. Been longing for a SWARM array. 👍