Any question answered...

Tubs do require more effort to repair, but you don't ride strada bianche every day do you?

Sealants like Vittoria Pit Stop do tend to repair most punctures, unless you tear or gash the tub, so are very useful.

Personally if it were me, I'd get a pair of light-ish aliminium factory built clinchers as the lower weight and stiffer ride would give you the performance boost you're after, with a lot less fuss. Anything from Campag/Fulcrum or Mavic would do the trick. I've a pair of Campag Eurus which I really rate, and a pair of Fulcrum Racing 3s which are also light and stiff.

Get a pump btw, as one day, and it will happen, your CO2 canister will fail and you'll be left stranded.

Some of the Easton EA range of wheels are very good too. I can personallly vouch for EA90SLX.