So, what do I think? Overall there is definitely an improvement in the bike and it's rideablility. It has NOT magically created more engine power, but it HAS changed the characteristics quite noticeably. How so? Well, I felt the power delivery is a lot more linear and predictable, and although I expected the AP to cause me some problems with breaking traction on loose surfaces when I snap the throttle, it did not do that once. What the AP did was get the power normally delivered after a second or two with the CV carb down when I wanted it. That change took me a while to get used to - for example, in the tight single track where I would normally hold the bike in 1st gear to keep the revs up I found I could actually ride a lot easier in 2nd gear without having to change down till there were gnarly corners and/or steeper uphills. Being able to stay the gear higher helped quite a lot with fatigue which for a fat bastard like me it a BIG bonus! We had to hop over several logs on the ride, and although I could not lift the front wheel by just snapping the throttle, doing that did lighten the wheel to make it easier to get over the logs - the predictable power delivery helped significantly compared with the CV when it came to log hopping. If I used humps to assist me, I could lift the front wheel pretty easily. This made negotiating braking/rolling bumps easier as I could just lift the wheel a bit and let the rear wheel follow the undulating ground and push me through - great for managing fatigue again
<snip>
So... for those of you considering the FCR35 for your bikes, the burning question is "is it worth it?" This is not an easy question to answer IMO, but I probably went through a bit more pain with my carb than most would thanks to my spigot issues. Here is my opinion:
Is the FCR35 worth it just for the performance increase - NO
Is the FCR35 worth it just for making the engine more predictable and usable - NO
Is the FCR35 easy to fit - NO
Is the FCR35 worth it from the "learning experience" - YES
Is the FCR35 worth fitting for the overall improvement in the engine - YES

If I knew it was going to be as much of a challenge before I bought the carb, would I do it again - I dunno. If I did not have the spigot adapter issues, I would say YES. It ended up costing me more than just getting Bill Blue's Mikuni pumper which should just be plug and play - so I would advise going that route if you aren't up for a challenge and want to save some money. I don't know if the FCR is any better or worse than the Mikuni, so please don't ask. It looks like there is a lot more info and advice out there for the Mikuni, but the info available on the FCR is VERY LIMITED. Hopefully this thread will help people in the future.