Some guys don't fly for several years and then move, and say it is no big deal. My sim partner was a P-3 driver and if he was working hard it at least didn't look like it to me--he did quite well. The time off wasn't that apparent. Another bro went from back of -10 to the MD11 and sailed through training.
Other guys have more trouble. The layoff seems to hurt.
In my case, I have been flying in the ANG, so it wasn't that bad. The challenge for me wasn't "mentally" keeping up with the airplane, but rather just the mechanical skills of learning to fly (specifically: land) an airplane that was about 3-5 times bigger than anything else I have ever flown. I knew my procedures, callouts, was smooth in the airwork, but I could still bounce a landing like you ready about. FDX has some great instructors, and my sim training went fine. However, after 12 years of flying one jet, you sort of fly by muscle memory and instinct. Now I'm having to mechanically learn new pictures, plus all that wierd stuff like one guy talks while another flies, etc. Also learning to use an AP, which believe it or not I've more or less never used in 25 years of flying (the F15 has a very simple attitude hold system that will hold altitude in level flight. No approach, climb, descent, or even heading capability). It wasn't easy, but it was fun. I'm sure there are some Chuck Yeager types out there who could bounce from plane to plane and be God-like, but as for me I was working the whole time.
