I’ve only done the tower thus far, but I saw no stringing on it. PETG by its very nature has a tendency to string anyway. I think retraction is really the key to reduce stringing: the default ABS retraction distance in Snapmaker3D is 4.5mm and I don’t recall the speed (50mm/s maybe?), but I was just using the defaults. Increasing temperature helps with bonding of layers.
I’d recommend running a temperature tower yourself. I used this one, which requires no special settings inside Snapmaker3D due to the Cura engine being used:
I went from 250 on the bottom to 230 on the top with 4 degree steps and there wasn’t a very big difference in quality between the different temperatures: one of the overhangs warped badly at 250 and I saw some bonding issues on the bridges at the lower temperatures. I’ll probably run this filament around 245, which is the temperature the filament manufacturer reports most people are using.