Yes. I upgraded mavericks to yosemite on an 11" 2011 mba. It works pretty good on that.
I also did a clean install onto a partition on a 2010 mbp which now dual boots yosemite and mountain lion, which also works pretty good.
I have also made a virtual machine of yosemite in vmware fusion, but that doesn't work very well.
I guess at this point I'm more curious how DP2 runs on 2011 Air since it just came out.
But those are still main concerns in the previous post ^^
DP2 is very smooth on my mid 2011 13 inch MBA, much better than DP1 and comparable to Mavericks
The scrolling on DP2 is pretty much as smooth as you could possibly imagine
Overall it's very smooth and I think it's even faster than Mavericks, which had that annoying stuttering when scrolling in launchpad.