XL rocks with PETG and (silk) PLA supports.
Guys, just to post my experience with the XL... I found the best use-case (for me) is supports! I print mostly PETG, and I found "Silk" PLA works amazingly well as an interface layer, and the multi-tool capability of the XL works perfect for this. As an example, walls/fill with black PETG, support with orange PETG, and interface with gray silk PLA:
I ran into some adhesion issues with PETG printing on top of regular PLA. It would kind of work at very low interface speeds, but was not that reliable (and also too slow). However, for some reason, PETG seems to lay down with no problem on silk PLA, even at full speed. Supports easily snap away leaving a nice, clean surface.
Am I 100% happy with Prusa? Unfortunately not, which you kind find my posts on the MK4S release if you want. I plan to eventually setup a MK4(S) with a MMU3 to be able to do this same thing. For the XL though, it may have it's complaints, but I'm very happy with it, as it's been an amazing machine for the few months I had it so far!
RE:
What settings do you use for the Silk PLA, interface layers, etc? I've used regular PLA as a support material in the past, but last night the PETG just wasn't sticking to it at all. I'm about to break out the BVOH. I'd much prefer the cheaper Silk PLA though if that works...