I just got the BG fit done yesterday. Bear in mind that my experiences are coming from a brand new rider, who hasn't even been on the road yet with my roadbike.

The fit does a great job of looking at your physical abilities and limitations and then matching the bike to them. You're getting a good fit 'by the numbers'. If there's a judgment call between personal opinion and the official numbers, the fitter is supposed to go by the numbers. This may have been more of an issue where I was, because the fitters at my LBS are getting officially certified by Specialized and have to send in their final numbers for 20 different fits, and I was one of them.

After I was done, I was chatting with another guy (who's VERY experienced in fitting, just not the BG way, and whom I really trust), and he said he would have changed a few things in the final setup for me. You can end up with the same results (for example) with the seat further up, back and stem longer or the seat further down, front, and stem shorter. He would have chosen the opposite one of the BG official choice, because of his experience.

My partner also had it done, and he's been road riding (and racing) for years and years. The BG fit wanted to change his riding style, and one of the store mangers had to actually come by and say: "you can't do that! He's been riding like that for years!!!" to the change the fitter wanted to do.

Hope that helps! I'm looking forward to actually riding my bike to see how it feels, rather than just being on the trainer. The nice thing is that I'll have a record of the numbers, so that if I do decide to make changes, I can always go back to the BG fit in the future.

In terms of a workout - it's as hard as you make it. They ask you to "pedal for a while", and resistance/cadence/effort is up to you. My partner worked harder than I did to really feel how the bike felt - and was even out of the saddle to test a new knee angle thing. I just pedaled lightly. It was about 45 minutes total of riding.