So I just started my first roll of eSun's PETG and I must say I like it. The only change in my settings that work great for PLA was to increase the temperature to 245C. There may be other temps that work that was just the first one I tried and it worked fine.
My first 20mm calibration cube printed at 19.95mm x 20.75mm. I could adjust it a little more by changing belt tightness but honestly my OCD isn't 'that' bad. I really really like my MendelMax 3. The output quality has been great out of the gate and I've had no issues with it whatsoever. I've gone through 4 and a half or so rolls of PLA and now working on the PETG.
I then printed some overhang tests and those printed perfectly as well up to 60 degrees. I haven't tried a bridge per se but I did print this bunny by Virtox and it printed great without any stringing between the openings.
In the interests of 'science' I crushed the little bunny and it took a surprising amount of force to crush such a flimsy looking print. I didn't take a picture before I crushed it so I'm using an image from the thingiverse post.
The diameter of my spool of filament was right at 1.74mm with minimal change over a couple of meters.
I did have a minor clog in the extruder nozzle from switching over from PLA, probably a tiny whisker of PLA left and when I heated it up to 245 it turned into glass. It wasn't a full clog, just enough to cause filament skipping on fast runs. I pulled the PETG out and then used a trick I've come up with using a single thread from a piece of steel cable. I don't have a drill that small obviously but that tiny thread of steel cable fits with only minimal space to spare and it worked pretty well to clean up the nozzle.
One thing I've noticed with PETG is that when doing an unclog procedure there's no stretch like you get with PLA and I'm sure it's leaving PETG in the nozzle. It doesn't look at all like the end of a PLA unclog pull. I was using 160C to do the unclog as a rough guess and there's almost no information online so I guess I guessed wrong.
But I got it cleaned up without have to disassemble my E3V6 head, which while it's an easy head to clean up, is still a bit of pain.
I've printed a couple of flashlight mounts, a skull to compare against the same skull I printed in PLA and it's all good.
I like it enough that I've ordered another couple of rolls in other colors from eSun and unless those just end up bad, I don't think I'll be going back to PLA any time soon. Maybe for a super detailed print since PLA supposedly prints finer than PETG but I haven't tested that directly.
And in theory if you get the clear/natural 'color' you can print food grade (again in theory) objects. I have no need to print something to eat or drink off/out of but there you go, it's possible if you need it.
One thing to note is that PETG prints fairly shiny and this exaggerates the layers of the print. It's no different than painting any material with a glossy material. Not sure there's a 'fix' for that other than possibly spray painting it with a flat color.