It can help a bit but it's not a magic bullet. You're usually not using that much plastic in infill to do a full purge, and the current implementation doesn't add more infill if there's more purge needed. Toolchangers stand to benefit the most from it since they only need to purge enough to prime the nozzle again.

There's also a side problem I've noticed with purge to infill, it's way less forgiving if your filament has too much colorant or you have your purge amounts wrong. Having a perfect print that had it's colors bleed sucks.

I never did try that. But I'm figuring out it needs a fairly big model (or several copies) to work properly and for the filament change time to be acceptable.

All in all, other than completely changing filament after a specific layer, I don't see the shortcome outweighing the benefits.

But in this case I've mentioned it becomes very handy. For instance, to print a PLA 1st layer for bead adhesion and then print ABS on top of it.