Err, well, it was actually Mark Twight's conclusion. I re-read his book over the holidays because I couldn't get out climbing, because I was in bed with the flu.
So I'm hip with all the funky quotes right now. Wanna know how many screamers to carry on an extreme alpine route? How about how much gu to eat every half hour and what intervals to set your heart rate monitor alarm to go off at and remind you to take a sip of water? Well, I know! I'm big on the academic stuff...
Seriously though, I like double ropes for reducing rope drag and doing double rappels. I only use a pair for alpine/trad climbing and only do that stuff well within my limits. When I run into a difficult move with a potential splatter below I'll start looking for a rap anchor long before I start contemplating anything close to a factor 1 fall, or any fall whatsoever onto pro that isn't bombproof. I'm not that brave...
The exception is right at the beginning where you're leaving the belay and there is always a possibility of a high factor fall - but those cases always involve both ropes and the concern is with the strength of the anchor.
However, I like to use a single 30 m half rope for easier alpine routes that are mostly 4th class but with short steps of up to mid 5th. You can simulclimb most of the way which is just a blast, and then set up a belay for the occasional step. Since the entire rack is available it's usually possible to get a very solid anchor.
But, this scenario has potential for a short fall directly onto the anchor, with a high fall factor - factor 2 if the belay were completely static and not through the anchor, maybe more like factor 1 given a proper belay.
I don't like to go more than 10' away from the belay without placing gear, and I stack the odds towards me by belaying through the anchor which I think is appropriate in this situation (maybe even through a screamer after all that reading - but that's not going to help the rope any).
What system do you use for climbs like this?