Hehe, I see… For most I think getting a separate old laptop is the way to go, unless you want some real challenge for days or even weeks :-)
Still have not gotten around to migrating my retina IMac to Qubes, but then again now it is not being used for stuff that I should keep separate…
As for dev stuff I guess it could be both perfect and cumbersome, although I do think it is perfect for especially prototyping & testing!