I've read the Vittoria Rally's, and Continental Comps are supposedly pretty tough. However, I do not ride tubulars.

If you want clinchers, you can get clincher rims like a Mavic open pro which could easily be rebuilt on that freewheel hub for not much money. They work just fine.

If puncture resistance is a major concern, then a clincher would alllow you to run Armadillos, or Conti Gator Skins, which are two of the best puncture resistant tires out there.