I'm working on three projects at present. They have little in common save for the one major hiccough: BIAB RealTrack timing &/or pitch issues.
Nothing MAJOR, but in one project the drums & held guitar, that come with a style, have timing issues that have to be addressed if I'm to use them together. The drums have a little swing to them and a little variation in the timing on top of that - good, very good, they sound humanly played. The guitar doesn't match the swing well, nor the variations or general chord change timing, (perhaps the way the segments were edited/sliced). Again these are things that say HUMAN but when an accent like a held power chord is late it is noticeable. When it's frequently, but erratically, late it's annoying. Normally I'd replace the part with my own playing bit the SOUND of this guitar is what I'm after so I have to go into very close detail editing the guitar to ensure that at least the more important, more noticeable accents are aligned. It's a drag, and given the variation in the drum track it's not a matter of simply pulling up to the nearest division.
Another track had a GREAT sounding bass part in BIAB but the pitch was out +8 to +17% throughout. That's not a lot I grant you, but noticeable to even my cloth ears given I was tracking & mixing, hence frequently exposed to it. Some of the walking parts between chords were a little odd too but I see & hear those as tension builders. I used Melodyne to pitch correct BUT, as you probably know, that program does subtle but noticeable things to tone. In editing for pitch I lost a chunk of the sound I was after so had to play it myself. I used the original bass part in Reaper to set up a preset in the free J.S Frequency Matcher so I could treat my bass part to get close to the tone of the BIAB one...SORT of successful but a drag.
In some ways it's rather like being in a band and recording, having to deal with people's variable skills and aesthetics as well as temperaments.
In that same song I found a pretty cool piano part that had the sound & style I was after but there were A LOT of extra notes - grace/passing/accidental/ghost - behind the actual chords. Some were cool but others clashed badly with the rest of the arrangement. I ended up using Melodyne to create a midi track of the piano part & then I manually edited the clangers, found a good sub of piano VSTi and things were much better.
BIAB is fab and these problems are small beans but do interrupt work flow a bit. A drag, but not insurmountable.

Cheers
rayc
"What's so funny about peace, love & understanding?" - N.Lowe