Domain mapping, Multi domain, network+, buddypress and multi-db

Hello,

Has anyone used the combination of domain mapping, multi-domain, network+ and buddypress?

I would like to setup several networks off a main-site and also use buddypress. However, I would like separate buddypress instance for each network. This will mean that we will have

Mainsite.com
subsite1.mainsite.com mapped to subsite1.com (This will have its own buddypress instance and also child sites e.g. childsite.subsite1.com). With this setup, I will not need the multi-domain plugin as each site will have its own registration etc.

Also will this work with multi-db? We are currently using w3 total cache so if the issues have been resolved with multi-db then that would be great.

Has anyone setup such a system or would I be better off setting up separate networks and finding a way to get the information onto the 'mother ship'

Thanks