blog isolation in multi-db config

We are using multi-db to segregate the tables spaces for our multisites.

Our understanding is that the multi-db schema is treated as a single large opaque "pool".

We want to be able to backup/restore per blog/site instance discretely.

Our use case requires that each blog/site in our network be discrete for privacy and portability.

VIP configuration looks like the path we should take.

Can VIP be conifgured and used independently of the "pool" configuration?

Does a VIP container *completely* contain a VIP blog/site? Or are there externalised elements not encompassed in the VIP table? (Think portablility - relocating a single blog to another server.)