Never heard that a single cam is more accurate. There is an advantage to double cams. When creep tuned, they can be setup to be more forgiving. Yes, string stretch can put the cams out of time, but they are out of time evenly. Where a single cam, you are putting one cam out of time.

I have both. I like both. My double cam mohave is more forgiving (probably due to 42" axle to axle), than my liberty, and its faster.