What is the max layer height people have used with this printer? Has anyone tried going up to 0.4mm? Higher than that?
Wondering how much I can speed up printing for some fairly large projects.
The factors you'd have to consider are that quality starts dropping after 1/2 of the nozzle diameter. If you're using the stock nozzle, that means you're not going to want to go much above .2mm (.2.5 or 3mm will probably be OK). If you have a .5 or .6, you can obviously expect to be able to go higher.
You can get a bigger nozzle, but that means you'll want to raise the temperature or slower the print speed some, as your filament will have less time in the hot end to melt enough for easy extrusion. Doubling the size of the nozzle will mean roughly quadrupling the amount of plastic going through the hole. That's why you'll see E3D Volcano and other large aftermarket hot ends with huge melt zones. I have another printer that's got a .8mm nozzle that I print at 60mm/s with, and it gets the job done considerably faster.
Plus side of wide nozzles is wide perimeters. You can shave a lot of time by using a .8mm nozzle with a single .8mm perimeter, and it's going to be just as strong as 3 .4mm perimeters.
Slowing the head down doesn't have as much impact to print time as one might think. Don't believe people who tell you they're printing at 120+mm/s. Unless they've done some crazy tuning in the firmware and printing something with no turns, corners, or curves, the head simply doesn't have enough travel distance to accelerate to that speed. Just because the slicer is set to 120mm+ doesn't mean the head is actually going that fast.
I know you probably wanted hard numbers with examples, but everyone's mileage varies a lot, and you're just going to have to experiment to get the best speed possible. Just don't be afraid to experiment and if a print goes bad, it's not a big deal.