hi michel, nice plugin you have!
i try it and found some question to ask:
1) it worked to me but it not take account of installed widgets and plugins options that seems very important
2) when a new user create a blog, i don't understand what you request because the Blog Templaete (optional) selector doesn't show any option->
Blog Template[Optional]: Select a template to apply: ??
What type of site are you creating? temp1, temp2
3) if create a site from user register method is ok, perhaps add a template selector to the admin create site page could be ussefull to.
any comment from you will be apreciated.
best regards, pescadito