My road bike is 650's. It's a gorgeously proportinate bike, too. My previous two road bikes had 700's and they looked odd in comparsion (small frame, big wheels).

I love the 650's and have had really no problems getting tubes. In fact, my first flat on this bike happened as I pulled into a rest stop on a century. The SAG at that stop actually had a 650 tube for me, so I didn't even need to use my own.

If you want fatter tires, finding bigger tubes/tires IS harder. But for a road bike with 23mm tires - it's really never been a problem (in 2.5 years). I do not have fenders on that bike - it only gets ridden in nice weather.

Honestly, in comparison to my commuter that has one 700 and one 24", two 650's is a piece of cake. Of course, if you have wheel troubles, stopping by a fellow cyclists house to borrow a wheel could be harder. Unless, of course, it's my house.