Its a difficult thing to quantify what exactly you get from better wheels.
I have R500s on my winter bike, good wheels for the money albeit heavy. I replaced my Ambrosios on my Bianchi for Fulcrum 5s. They are noticeably lighter, let alone how much lighter the 3s will be.
But, 'feeling' any great difference is difficult. I console myself (console myself is the wrong word, but you know what I mean) that despite my spending less time on the bike, my fitness is shot compared to two years ago...I can still maintain decent speed on the bike, just nowhere near as long as I used to be able to. Why is that ? Is it the better wheelset ?
Two things with Fulcrums, read the specs on their website, they do have recommended rider weights, ..and they are strong, certainly the 5s are. Used (and slighly abused) mine commuting, they held up admirably.