As the organizer of the NYC meetup, this is something I've struggled with how to handle. My company, Yapp, uses both Sproutcore and Ember, so we have a vested interest in both projects have a thriving local ecosystem. I'm open to ideas about how best to accomplish that, and I'm not comfortable that my current ad hoc approach is the right way to go.
Before I inherited organizing the Sproutcore NYC meetup, it had had exactly zero events in the preceding 6 months and 2 in the previous 12 months. Of the two people responsible for organizing those events, one is no longer working with Sproutcore, and one moved to the West Coast. Basically, there wasn't an organized community to speak of.
As I've spoken to local developers, there is a lot of excitement and interest in Ember.js topics. The big topic on people's mind here is Backbone vs. Ember. People with Sproutcore experience have a leg up in learning Ember, because of the common heritage and KVO/object model primitives.
At our last event, we had a talk about the Ember.js StateManager with some references to Sproutcore Statecharts, as well as two lightning talks: one was a demo of a Sproutcore app and update on 1.8 from Tim Evans and one was an experience report from a new Ember.js user about issues he ran into on his first project.
I could split the groups into two. If I do, I think we would have a well-attended Ember.js meetup and an anemic Sproutcore meetup. It also is basically double the work and cost for me as an organizer to do that.
On the other hand, I understand that having the groups combined might be confusing to outsiders and am sensitive to the need for clarity.
I'd love to hear people's thoughts, especially from the New Yorkers on this list and from other people running active Sproutcore meetups.
Best,
Luke