With 1541U2/Ultimate64 you have to explicitly save the cartridge contents after saving the game. The saved game is never stored in the existing .crt file, but if you save the cartridge contents in a new .crt file, it will contain the save game. IMO this is not very convenient and you can indeed consider to use a D64 file. Personally I consider Briley Witch Chronicles a big enough game to build a dedicated cartridge. I did play BWC1 from a dedicated cart and will do again with BWC2. I can now use my own designed device for that, the EasyFlash 1CR.