You get more benefit from aero front wheel than rear. I have the Cadence Aero rim on as a rear wheel, and would not hesitate to use it as a front (it is coupled with a Velocity Fusion now). That 30mm profile has never been noticeable to me, in comparison to my A23 based wheel set, but I am heavier than you. My cadence aero / Fusion set is 28/32, and has so far been very sturdy at my 205-210 lbs, so you probably wouldn't hurt a thing at 24/28, granted that the 28 rear rules out Shimano hubs.