I have a bart pre in my Sei and it's something I want to change, it's not the most effective pre i've used, I've had far better results from East pre's in the past, for example, tghe top end seems all or nothing at times.
I would wait for a second hand east to show up just to give it a go, if it doesn't work then you will be able to pas it on easily.
My pentabuzz works well in my band with stock pre, wish it had a mid control though, but I can get what I want out of it with a slight mid boost on my TD650. Running through 2 x 4x10's does give it some punch as well
Hows the poly coating holding out on your buzz, I've just had mine removed, there was somewear and it was buzzing too much, had to roll the top end off to make it palyheable, now it's back to ebony and it sounds sweet. Probably gonna try some ground wounds to see how they sound and protect the neck as I do like to dig in a bit!
Cheers
Tony