One caveat, as gleaned from the Class::DBI source code - this approach seems to leak memory "on older perls", whatever versions that might be. Other than that, I think your approach is fine, as it does automagic cleanup/restoration of the previous state.

I think that you got the AutoCommit thing wrong though - AutoCommit should be a false value if you want to issue your transaction statements (begin transaction/commit transaction) yourself. But DBI will warn you about ineffective commit statements anyway.