My hybrids are fine - the 21 remains at D3 (I have it set to 39" length) and the 27 has always been C3. I hit both dead straight.
I played with a TM Burner 7 wood before switching to the 910F 19*. I've pretty much established that 41" and a 59.5 lie angle are my fit. I found D2 to be the best overall hitting because I hit it dead straight off the tee and it launches pretty well from the deck. At A2 I have a lower, more penetrating ball flight on the tee but find it hard to hit off the deck. If I use D3 - close to a snap hook. Using C3 gives a similar ball flight as A2 but I tend to have too steep of a downswing and end up chunking it from the deck.
Why would I be getting a higher ball flight with a lower loft? My guess is that a more open clubface does it. Also it is easier to launch it with the lower loft.
When I initially bought the 910F, I set it up for 41.5" length - it was at the B3 setting for a long time; could hit it great off the tee but didn't hit it cleanly on the fairway. It did feel like I was losing balance on any of the standard lie settings and I was hitting it all over the place - I somehow developed an occasional snap hook about a couple months ago and it felt like I was fighting my grip when hitting ball (this was an issue I had about 4 years ago and my grip was so strong that the right hand almost laid flat). I also found out my stance was gradually flattening and I started having a tendency to hook or pull.
About a month ago I shortened the shaft length to 41" and started hitting the ball cleanly off the deck. The problem with the snap hook went away because I moved the ball forward a bit in relation to the upper body - so one of my checks is to make sure 2 knuckles show on RH. I played it at D3 last golf game and did OK on hitting but generally the ball flight off the deck had been a bit low and a bit of a draw but with a tendency for a hook.
Was hitting it at C3 yesterday and generally tee shots had low trajectory with a draw (reasonable distance) and deck shots were low or sometimes not cleanly hit. Just on a whim yesterday I set it to D2 and it hit very clean off the deck and dead straight as did tee shots with a higher ball flight and I stuck with it for two driving range sessions; I tried A2 with tee shots and it felt more powerful but didn't hit cleanly as D2 off the deck (I was hitting them off the grass; may have to do the Sorrento Canyon test this weekend - this driving range has thin mats and a passing grade is to hit it cleanly).
Like I said at the beginning, my setting with the hybrids have been fixed for about 6 months now. Historically I have been a good fairway wood player and tended to hit straight or a small fade before going to the 910F. I used to play a slightly closed stance with the fairways before (had a TM Burner 7 wood that I just about never missed with). The thing about the 910F is when I hit it properly the distance is much better - I can nail it!
I'm probably going to end up closing this topic with this response - the anomaly can be attributed to a swing fault. A range session after this AM's game (which was 4 strokes off my norm) seemed to fix it.