Hmm. At first I got excited, but am a little confused. The already recorded DI track is "essentially" the same signal as what came out of the guitar before the amp. When I re-amp, it allows me to comfortably try different mics, placement, and different amps, then re-record on to another track. Since the recorded DI track is "essentially" the same signal as what came out of the guitar, why would you need to have access to the guitar again? There is something I am missing here
First off, let's be sure you're in the right ballpark. The ToneDexter is, as far as I know, intended to work with acoustic guitars that have a built-in piezo pickup. In principle, it could work with an electric guitar or an acoustic guitar with a magnetic pickup, but the software isn't designed for that kind of sound. When most of us think of re-amping, it's to take the DI-recorded output of an electric guitar's pickup, play that back into a guitar amplifier or six, maybe through an effect or eight, put a mic or ten on the amplifier(s), and record that.
With the ToneDexter, if you had an acoustic guitar with a piezo pickup and you recorded it on two tracks, one direct from the pickup and the other from a mic on the guitar chosen and set up so you think the sound from the mic is pretty darn good, you could use those two tracks to create a wave map and use that to de-quack the pickup track.
To do what I think you'd like to do, you'd want to make a few different wave maps so you could choose which one gives you the best sound for a particular track. And to do that, you'd need to have recorded not just two tracks of the guitar, but one with the pickup and a few others with assorted mics in different positions. And if you're going to do that, you might as well just pick the mic track that sounds best on the song, or combine them, and maybe add in a little of the pickup.
As I see it, you'd get the most mileage from the ToneDexter for live playing, or for easily recording a good sounding track of a guitar that you've mapped. You could have a couple of maps for your guitar, another one for your mandolin, another one for your uke, and use them when you're playing live. It's a multi-purpose signal processor, but not a general purpose one.