@ipaschke Hm, I use a PiZero on my Pi1541 and have had very little trouble running demos. However I must admit that it sees very little use these days, as I run almost everything from real floppies... But eventually those will run out, so Pi1541 it will be. :)
I will have to test Next Level some time. Only watched it on floppy so far. But even with real floppies the IRQ loaders have issues. Krill's loader used to be a bit picky, producing garbage on some of my wonky drives. He fixed that, though