I bought a Prusa MK4! I was on the waiting list for a prusa XL. It's really quite expensive - with still no real ETA - and this came out for a lot less. So I switched my order. Just figuring it all out. It's working...
Ok real life prints with the MK4 0.4mm nozzle. 1 hour 39min. On the MK3S+ similar settings 1 hour 56 min. I thought it would be better. I'll keep trying and investigating. These are extreme parts very flat 2mm thick.
When printing large flat pieces I had troubles with curling/lifting (petg mostly). The solution that works for me is to add mouse ears (Google it) to my design and print them 0.4mm (two layers ) high. I put them on any 90 degree corner, so on a square I’d add four .
When the print is done i just cut them off with a utility knife. Sometimes you can break them off by folding them over
I think the circle shape bleeds heat slower. And if anything lifts it is usually the edge of the ear