Recording Slow, Then Speeding Up

Hey, all. I've got an upcoming project that will involve a clarinetist performing all 11 parts of a composition. He's created time signature maps (gazillions of changes), and will of course be playing to a click, but he's informed me some sections are impossible for him to play at tempo, so we'll need to slow the some of the tempos down for recording. I use Logic almost exclusively for MIDI composition, so this is new territory for me. I've read through some threads similar to this and come away with no consensus. What's the currently recommended method for the least amount of artifacts?

- Make sure the section to be sped up will be recorded separately

- Lower the tempo just enough that he can adequately play it. Speeding up more than absolutely necessary will make the cheat clearly audible.

- If you have a Tempo Map with more than one entry, duplicate that Tempo Map and adjust the Tempo Change(s) for that section accordingly, so you can switch back and forth between record- and playback-tempo.

- Prepare a second track to record the slowed down parts, then engage GlobalFlex View at 1, then Track Flex at 2 (monophonic will be fine) and finally Region Flex at 3:

 

- If you restore the original Tempo, these parts will speed up.

- Record all the slowed down parts to that track, all the normal parts to a regular, unflexed track.

Thanks much, Christian (and for posting in both forums) I'll need to study this and do some experimentation. So it looks like relying on Flex, rather than Vari Speed, is the best bet. Also, by recording 'separately' I assume you're talking about dedicated tracks, as opposed to in a separate project or at the end of a project, correct? I was a little concerned that altering tempos in the middle of a timeline might cause sync issues down the line, but it would certainly be more convenient if we could keep everything in its proper chronological order. Unfortunately he's talking about as much as a 20% change in tempo, which I have very little hope of sounding acceptable.

Yes, dedicated tracks.