You could try installing the Widget Manager plugin. It looks like it's not posted on the downloads page anymore, but I have a copy and it works on the latest version of b2evo. It allows you to copy widgets from one blog to another. It wouldn't work automatically when new blogs are created but I've found it a lifesaver when needing to copy bunches of widgets across pages without having to do it one at a time as the core works currently.

• widgetmanager_plugin.zip (9.2 KB)

Thanks @fredsy, it is a useful plugin indeed.

The source code of this plugin was missing in the site, but now that you shared it, its post has been updated: http://plugins.b2evolution.net/widget_manager

@caiken how do you create the per-user blogs? do you use a plugin or just create them one by one?