Not sure the comments on clinchers being easier to replace. I used to think that before I attended seminars and really started getting the feel.
Tubulars definitely require a little more prep-work with "pre-gluing" the tires, but seriously, replacing a tublar comes down to:
1) Breaking the bead
2) Yank off old tire
3) Add little bit of air to new tire
4) Pull on.
5) Inflate fully and go
I have had a much harder time with Clinchers, getting the tire back on, especially with some like the Michelin Pro Race 3s, as well as subsequent pinch flats.
Practice makes perfect. but I have seen experienced roadies change a tublar in about 15 seconds once the wheel is off.
Your experience may vary... I train on clinchers, but race on tubular