Yeah, when my trans died a couple months ago I narrowed it down to John Wood and BTS like everyone else. I happened to dial John's shop first and after he spent an hour on the phone explaining things to me and answering questions (not just trans questions), I went ahead and bought a trans from him right then. Glad I went with him, since I proceeded to screw up the front pump and TC on his brand new trans when I botched the first install. John went out of his way to help me, sent a new TC and pump, then the next day he leaves me a message out of the blue "hey I'm having a trans company send you a manual on 4R100 trans teardown so you'll have some pictures to look at. Call me when you're ready to work on it and I'll walk you through it over the phone". Installed it right the second time and trans works great. Really felt nice having someone on the opposite side of the country do that for you.
Also, I remember shipping on the trans (Fedex freight) was like $600 roundtrip (shipping to me and return of old trans). Shipping bill said 275 lbs, and that was Holtville CA to my house in Leesburg, VA (opposite side of the country).
Not trying to steer you away from BTS - just plugging JW since he helped me a lot. When I was soliciting input, it seemed to me like most western people go to JW and most eastern people go to BTS.
Good luck!
Ben