Starting from a level playing field, and assuming from scratch, if a pilot has not flown FS, and he's up against one that has, he will be at a disadvantage. A substantial one.
I tried to find my post on going to LBA for a check-ride, but couldn't. It was about not having flown for many, many years. Because of not knowing FS very well, I was lazy about setting new winds. I hung around a simulated LBA for quite a few hours with 30kts at 2,000 across the ILS. When I got there, that's exactly what I'd got!
PB took me around the circuit a few times and on one arrival at the NDB he said, "you're freaking me out! You're arriving at the beacon within 2 seconds every time." What's more, I was chatting merrily away about this and that while I did it. FS had virtually (ho ho) removed the workload.