A few more questions:
1) Are the focusing screens form older models compatible with AFD?
2) Has anybody used TTL flashes from other brands with AFD on a hot shoe (like canon's 580ex)? The manual says doing so may damage the camera. I have used 580ex on my bronica sq-ai and it works fine in manual mode (though prism's meter gets crazy but it seems quite simple to figure out the right compensation). Is it safe to do this on AFD?
Lot's of good comments thus far. I'll add my two cents. I previously owned a AF. I wouldn't recommend it for anything digital. I then bought an AFD and this was truly a step up. I just recently purchased Jack's AFDII and this brings the menu of customizable options to the upgrade. Focus is ever-so slightly faster than the AFD.
I own the 55mm, 80mm, 150mm, 55-110mm and the 110-210mm lenses. The primes give the best image quality and the 55mm is downright wonderful for the price. The 80 is very solid too. The 55-110 is a good, but not great, quality "walkaround" lens if you're looking for that.
AK, since I 'upgraded' to the AFDII, I'm considering selling my AFD with an 80mm prime lens very soon (next week when I return to CA). If you are interested, PM me. I can cut a good deal, since Jack gave me a solid deal on his AFDII.
Regarding your questions above, I'd stick to the AFD and newer focusing screens but the system is the same from the AF thru the AFDIII (I'm nearly positive on this). Regarding flash units, I'd recommend using a Metz system. I use a 54zi with the SCA adapter and it works quite well for a stand alone, system directly attached to the camera. You find the Metz systems on the 'Bay every once in a while.
My ultimate opinion is that the AFD system is a great entry into MF digital work. Good luck and enjoy!