Yeah, I've been super happy since switching to it. Javascript still has it's ugly warts, but overall I think time to develop apps has dropped dramatically!
I think it will be a pretty sizeable jump (100% growth?). I expect the next 0.8 release will make a lot of noise when they leave Handlebars behind and really ramp up the rendering engine side of things.
Yea, I wouldn't call them big either, but they happen none-the-less. For package developers it can be vital. Sometimes A must be loaded for B. It's mainly a third party javascript issue. The compatibility folder sometimes does the trick, but by contrast the same utility doesn't exist for package developers. It's a larger dependancy management issue not tackled by the current packaging system.
I'm excited to see what the future of Meteor and Meteor-like frameworks hold.