I debated whether to post this in P1 or AMS, but here it is. I’ve had my P1S/AMS for about four months now, and I really love it, except…I don’t do a lot of multi-colored prints, and the fact that the printer/AMS retracks the filament all the way back, after every print, even if the next model is going to be in the same color, is very annoying. There was a post about this several years ago, but there was no resolution. I could live with the extra time it takes if that’s all it was. I have had problems with the last several filament refills I’ve bought from Bambu Labs (they’re replacing one of them) where the filament keeps getting jammed between the filament roll and the spool (yes, I read the instructions on their wiki page). The jamming is made so much worse by the fact that this retraction cycle happens for every model I print. I wish there was a way to tell the printer/AMS that if I’m just going to be printing with one color don’t retract between models. I have laser software that allows me to change profiles depending on what I’m doing (rotary or non-rotary), it would be nice if there was a way edit the start/end Gcode so that I could switch between the two modes. On a side note, it seems that the two motors in the AMS aren’t synced very well, the filament motor is pulling filament back faster than the spool motor can handle. This has led to a lot of cross-over issues during the retraction cycle. I’m curious if anyone else is having the same problem? End of rant (sorry for the long post).
I, too, noticed that retraction is causing issues with filament being discharged faster than the spool motor can handle, to the point where I’ve had it completely jump off the spool (so far, this has happened only once).
If you are printing something that has two colors on each layer laid down, you are going to find that (1) it takes forever + 3 days to print, and (2) the amount of waste material is astonishing. For example, if you print this Pistachio Bowl 2.5 by EPIQ3D - MakerWorld in two colors, such as the blue & white shown, you will find that the amount of filament waste is phenomenal! Lesson learned! 
The last multi-color print I did was months ago (Boat Model 010 - The windup-motor boat by vandragon_de - MakerWorld) and it took forever. I normally print in one color (black or silver or whatever) until it’s gone, so this constant feeding and retracting is a time suck, and on a nearly full spool it can have catastrophic consequences (as you mentioned). I guess one way around it is to feed it in from my Sunlu drybox, but that defeats the purpose of having an AMS. This machine has such phenomenal capabilities, I just don’t use them (well, except for the motorboat) because of the time it takes and the amount of filament waste it produces.
Many of my prints are also one or two colors. For example, I have a product whose face plate is flat. I print that in red, and then the company name in white script. Not much waste there at all since it is a single color swap. But imagine rotating that object 90 so that the face surface is now vertical instead of horizontal. Printing the same white script would be distributed over many layers, and that would require many filament swaps. So doing multiple color prints requires so thought as to object orientation to get the least number of filament swaps & thus least waste and least time.
I must say, the Bambu does a MUCH better job with the text than does my Prusa i3 MKS+, which cost most than my Bambu P1S with AMS combined and only prints in a single color.
The trade-off for me seems to be the filament waste vs the quality of the print, so for my business printing, that is more than OK since filament really isn’t expensive.