My setup is 5.1 with TLE-1 sub-woofer.
I'm about to replace my FB1s with OB1s, and use the FB1s as surrounds (replacing TB1s). I don't think it's overkill!
The centre will remain a TB1 until the OB1 centre is released.
I use a Bryston 4B-ST to drive the fronts, with a 3ch 5B-ST for centre/surrounds. I'll sell the 5B and get a 6B-SST to drive the front/centre, and use the 4B for the surrounds.
I used to have a mis-mash of surround/centre speakers (and amps) with the FB1s, but when I got all PMC/Bryston (inc SP1.7), there was an immense improvement in the seamlessness of the surround soundstage.
What amplifier to get? A 5ch 9B-SST, or if you want more power, a 6B-SST plus 4B-SST, or five PowerPac 300-SST.
ps I envy you your 7B-STs!