I love my Klasse (original). While I've only used mine for about 6 rolls of film so far, it has easily become one of my all-time favorite cameras. If you can justify the extra $200 for the custom functions, go for it. Usually, I just leave the flash on auto and if I really don't want flash, I just turn it off. In my experience, with this camera, I've found that it will typically default to shooting with the widest aperture possible to keep the shutter speed up and the flash off, only resorting to flash if completely necessary. Some of my favorite images with this camera were with the flash directly on my subject though so it can work to your advantage...
I'd go for the original if you can find one. They're amazing cameras. And, as stated earlier, the Rollei AFM35 is the same camera with a different/better lens coating, but I think the Klasse is much nicer-looking in all black.