Aero helmet recommendation?

I have a TT frankenbike now (repaired frame Ruby with TT "front end") and borrowed a friend's Louis Garneau aero helmet this weekend. What an improvement! But his 2004 helmet was WAY heavier than my GF's Giro aero helmet from 2008. I tried on someone else's Rudy aero helmet. The LG helmet was the most comfortable of the 3. Anyone have any advice or tips on current aero helmet recommendations? There really isn't anywhere in Santa Barbara that carries more than maybe one aero helmet (giro) My mechanic told me that the helmets with the goggle like visors attached are more aero than wearing sunglasses. Since I wear Rx sunglasses, I may not find a helmet with a visor that fits over my sunglasses. Thanks for any tips! Tokie