Hi there again Kristian,
I admit I am not the most techical tri-geek at all, I have no idea on what is faster and has a lower rolling resistance or which pressure is the best and yada yada yada, but what I do is to train on clinchers, actually a bomb-proof tyre that won´t get flat easily, it doesn´t matter if its super heavy combo of wheel and tyre. AND get a racing wheelset, with lighter and fast tyres. Tubular V Clinchers, there are pros and cons, for you, you would be better with a clincher racing wheelset, your questions is your answer, if you are confident you can change a clincher without problems, go for it, there are some sweet clincher wheels out there.
Or once you figure out how to easily change a tubbie, its suppose to be faster to change, Reinaldo Colucci had a flat at IronmanBrazil and took him less than 5 minutes to do everything. Or maybe, ask Normann Stadler how easy it was in Hawaii 2005, do you remember him trying to get his tubbies out of the rim with a stick? He couldn´t pull that tubbie for nothing in this world, so don´t worry, the guy is a 2x world champion and haven´t figured out the tubbie thing, you are not alone, that´s for sure.!