All the billm mods are well thought-out and tested. Bill has modded literally 1000s of BJr’s. The bias mod makes the BJr into a way better and more versatile amp, and as long as you are doing that, you might as well do some of the others too. The “Clean Boost” add-on board is really a usable addition, adding about 10-11 db volume and makes it a workable gigging amp if you have to keep up with a loud-ish drummer. I’ve modded 7-8 of them myself and I’ve never heard anything but compliments about them.
If anyone else is interested in doing a BJr, buy one cheap, (you can find them with broken reverb all over the place) and do the mods. I’ve repaired several with broken reverb (easy and quick fix) for free and even if you end up replacing the reverb tank, a new one from AES is around $20.00 and much more durable than the original.
Except for the transformer upgrades and the power tube (to 6L6s)swap, I think I’ve done all the mods on one BJr or another.