I'm using 4.0.10 - latest stable everything. I reported previously the SVN issues when adding new files they get a ? instead of the + (add). It bit me again last night! I added a new view controller in my storyboard (xcode) and I get home and can't continue working (build) because the designer had a ? which I obviously didn't see as the item is collapsed by default (designers don't show).
I used the alpha 4.1.x for a while until the recent stable releases with async support and it worked great. If the new storyboard features are what's holding back a XS update, please consider hiding the new storyboard support and push out a XS stable update then resume work on the new storyboard editor. We really need XS to be more stable. Respectfully, it always feels unstable and like a beta and I really home soon XS will feel like a production professional project and break free from the MonoDevelop open source past. It's the weakest link sadly, the most visible element of course as it's the IDE. Please put the resources to this to get it to professional and stable level.