Finally, I would much rather flat on a tubular at high speeds, they are much more likely to keep rubber on the road than a clincher. If you want, I probably could find a picture of the ag2r rider who had a nasty crash on clinchers at the Giro. So no, a clincher is not safer.
I see only three possible downsides to tubulars; They are pricey compared to clinchers. Set-up time is longer than clinchers, it doesn't matter to me but it may matter to some. Patching a tubular is a pain in the ass but I can pay a guy $16 to do it for me - I guess that goes back to my pricey point so there are really only 2 inconveniences with tubulars
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The safety issues are different with clinchers than tubulars -
Descending on a hot road with clinchers you have to watch out for blowouts; with tubulars you have to watch out for glue melting and tire creep. But a front tire flat going around a curve - yeah I'd rather be on a sewup; clinchers are much more likely to go instantly flat and sewups are more likely to take their time losing pressure.
And patching tubulars is a pain but it's a bit of craftsmanship and history and I kind of like it. I'd be on tubulars all the time if it weren't for the cost.