I've never bought into the decreased sensitivity argument. It's exactly like the HIV or cleanliness argument on the other side.
I've experienced both there is no difference. I think its a mental thing and totally depends on how you identify with your own penis. If you think you should have a foreskin and dont, restoration will mentally change your outlook and of course you will enjoy sex more. Its the same thing with a guy who is gay and has sex with a woman. He may never cum or even get aroused but with a man he may cum explosively and need to go multiple rounds. Personally I feel sexual response is more a mental thing and less of do I have this part of skin or not...
I agree that there is likely a mental aspect at play here as well. However, my positive results are not only associated with improved sensitivity. I feel a greater interaction and response between my skin and my glans. Greater, skin mobility has contributed to this as well as changing the dynamic mechanics of unprotected heterosexual style of sex (not sure if similar results would be obtained in other styles).