I've had a lot of experience on both Flight Sim. 2004, and Flight Sim. X. I know that you can create a log book, but once you do, you can't determine which of those hours were gained by speeding up the simulation rate. So in my opinion (although I myself have booked a lot of hours on the game) at the end of the day, the hours mean nothing. However, that's not to say that Flight Sims. aren't a great way of gaining expeience with different aircraft and the way they operate (not to mention that they're awesome good time!!!).