Hi Chris,
Doesn't it seem that no subject in music causes more debate than tempo in Bach?
With the possible exception of the Book I prelude, I wouldn't quibble over any of your tempos here in the abstract. The only thing I might suggest considering in some instances is whether, given your technique/preparation, certain of the tempos are too fast for right now, even if you are conceiving of an ideal tempo. In other words, as someone once advised me when I was preparing for a performance, "Never show an audience what you can't do."
I don't mean this to sound harsh. It's just that I hear many very good aspects in your playing, for instance with the voicing, that you would want to come across in the best possible light, without the slowings, unevenness, and asynchronicity between the hands. Not that anyone will be close to perfect in these regards, it's only when it's too much that it may be a problem.
Book I Prelude: As noted above, this is the only place I might say I don't think your tempo works (in the first section), if only because I'm not sure anyone can get in all the trills/rhythms in the right hand and make it all sound graceful. I've always found this an odd piece for Bach; it's one of the few where I think of the left hand as more of an undulating accompanimental figure (almost like a Chopin nocturne perhaps) rather than a voice of equal value. So I might suggest thinking a bit more about balance (i.e., left hand quieter?). Your technique seems all there in this first section. I just would say you need to slow down a tad and think more about the phrases, and then the ornaments/thirty-seconds will sound less harried. The presto's certainly not easy, and you start off fine, you just seem to get a bit bogged down in places tempowise.
Book I Fugue: Good job here overall. Personally, I might like to hear a bit more vigor and firey drive in this piece, but that's just personal opinion. The only I might advise is that your left hand could be a bit crisper and less noodley in a few places.
Book II Prelude: I like the tempo and some passages are very solid, but it puzzles me that other passages are rather flubbed and uneven. Maybe it's just a matter of finding those and practicing them more? In other words I think you have the right idea on this piece, I think it just needs to feel more secure perhaps, both in terms of internal evenness and overall tempo, which seems to get a bit bogged down in the second half. One detail I heard also that sounded odd is the extended trills, it seemed that the right hand trill was significantly faster than the left.
Book II Fugue: Personally, I think your voicing is great here. Some will disagree of course, but I think Bach voicing should never be brought out self-consciously, you just have to hear them as he wrote them, and I think you accomplish that. Again, the only things that are distracting me are places where notes drop out, unevennesses, and some hand-breaking/asynchronicity (practice left and right hand separately more?), particularly toward the end.
Anyway, I don't mean to nitpick too much. I like the direct, unaffected quality of your Bach; in these, I just sometimes find the technical elements a bit distracting.
Joe