I'm just getting started with a Qidi FF Creator Pro / Dual clone using MakerBot software. I have printed in PLA and found that it works really well, the 20 mm hollow cube is near perfect in PLA at 215 C nozzle and 40 C build plate (mine comes with the blue surface) with a near perfectly flat roof and dimensionally accurate.

Now I'm trying to switch over to PETG (a eSun reel I bought from Amazon). I tried the 20 mm hollow cube in PETG with a 70 C plate temp and the following results:
Nozzle 230 no turbo fan - printed OK but the roof was saggy.
Nozzle 249 no turbo fan - printed OK but the roof was very saggy and I couldn't get the raft to separate from the cube.
Nozzle 240 with turbo fan - printed OK, the roof was saggy, I could separate from the raft.

I suppose that it's unreasonable to expect PETG to print a roof with no supports but I'm interested in any comments on what I might try next.