Actually what you're doing in MoI 2 (which I've not played with -- too happy with 1.1 I guess ;-) ) sounds better than what I'm asking for.

The automatic split I'm thinking of might be either (a) driven by explicit "seams" you designate inside MoI (that don't do anything except drive splitting), or (b) material boundaries (can MoI v1.x handle materials? I haven't found this feature).