I have spent several days trying to setup the dual extruder, it fails every time.
The filament does not adhere to the sheet and ends around the nozzle. This is the biggest piece of junk.
Also comparing the speed of the snapmaker a350 with other printers, what it takes 1-1/2 hour in other printers it will take 11 hours in the snapmaker.
Will be using something else in the future, way to expensive for what it does.
You may need to adjust the Z-offset on the fly. It sounds like your’s is to high, which unfortunately is a common problem - mine after Auto-Z-calibration is usually 0.3-0.4 mm too high. I hope Snapmaker will at some point find the reason for that and correct its firmware.
Regarding speed: A factor 10 suggests you are comparing apples and oranges, i.e. the Snapmaker high quality mode to a Bambu Lab draft mode. Still, Snapmaker is not the fastest 3D printer on earth - for obvious reasons: It is a 3-in-1 machine, which means compromises. If you only aim for 3D printing, indeed the Snapmaker was the wrong choice. Perhaps do a bit more research before your next purchase.