I have actually managed to debug something in an impromptu setting with that Velleman pocket scope. It suffers a bit from the button interface, and the lone channel, but it is really super-portable. It was definitely better than nothing.
That said, I have found the Rigol 1052e fits in a backpack like nothing, and is very light and compact. Out-of-budget in this case, I suppose, but having a real scope around can be a real boon.