me too. i actually did a search earlier today for this exact topic. i'm running aksiums right now so any wheel will probably be a weight improvement and/or aero improvement. to me, the 3.0sl's seem to be the best bet; roughly 2/3 of a pound lighter than the 4.0s and only 1cm difference in depth (assuming i'm understanding the depths correctly). am i off base in my logic? i have a pair of xero xr-1 wheels but am not a fan and will be selling them but i do like the deep rim though.