Documentation states "supported file types Disk image (D64, D71, D81)"
Are multi-part titles - as long as standard kernal load/save routines are being used - fully supported right now?
Or differently phrased: Do multi-part titles which work on SD2IEC work on KFF as well?
SD2IEC compatibility with disc games (you call them multi-part titles) is 78%.
Kung Fu Flash compatibility with disc games is half of that.
KFF cartridge doesn't use IEC port - using cartridge port allowing to play disc games using Kernal routines only.
Very similar results you have with BackBit cartridge regarding disc game compatibility.
On other hand, 83% of disc games that work with KFF/Backbit cartridge have instant loading time natively - it's much better than SD2IEC combined with Epyx Fastload cartridge, even with JiffyDOS too.
These cartridges don't speed up just loading time of main file of disc games (like Epyx Fastload or JiffyDOS do), but all of them are loading instantly.
Other 17% of disc games KFF/BB cartridge load main fle instantly, so it's still faster then SD2IEC with Epyx FL or Jiffy.
For disc games that don't work with SD2IEC/KFF proper fixes need to be done for each of them in code (Easyflash releases or versions of disc games that don't use Fastload routines of 1541 floppy drive).
So, basically, we're almost stuck at these percentages, because present C64 scene doing new disc game releases is not big enough to fix games that don't work with SD2IEC/KFF cartridge.
We have on yearly basis around 40 new Easyflash releases (thanks again to Master, The Joker, Knight Rider, CSixx for making them) and maybe 10 versions of disc games that will work with SD2IEC or KFF without having them already in SD2IEC/KFF Nirvana collections you can find on F64 Wolke.
And there are around 2.460 disc games for C64..