I use the stealth model with the harness etc. If you have a 99-01 FLH with the M/M throttle body I have a PC III usb I'll sell ya cheap. I use the DFO just cause it is pretty much fool proof. It is a load based system so it knows when there is a different load on the engine such as 2 up riding or going up hill etc. I like it. I don't see the need to exactly get the fuel correct in the exact amount at every rpm range. Just doesn't make sense to me.
Some people argue for the PCIII but mine was way more trouble than it was worth. For instance, I paid just about 350 even for the thing. Put it on my bike, took it to a PC teaching establishment and after 3 hours they didn't even come close to getting it right. They didn't have a dyno though. Then I find out it will cost upwards of 400 bucks to program the bike for my engine build. SO that is an extra 750 bucks on top of what I already spent on my build.
I hear all the time how people malign the DFO. Well I am here to tell ya, I am getting better than 40 mpg's. on my bike with my build which I think is excellant. I get excellant throttle response from it, I have no back firing, pinging, or fart or burps at all. Cost me 125 bucks used in the box. Took me a bit to figure out exactly how to tune it and several tries to get it where I want it. I even wrote a blurb here on how frustrated I was with it. The thing is is you have to set it up exactly as they say. No leaks of any kind, your bike has to be warm, with the M/M the idle has to be correct and well you get the idea. ONce I had these issue squared away bingo, I am a happy camper with it. keepem sharp