I just think that if you have some proposal, than you should
be aware of all consequnces and be more specific about exact behavior.
E.g.
- if you commit inside SP, what will happen to subsequent commands in SP,
will they raise exception ?
- how do you notify client that his transaction ended ?
- currently when you start transaction, execute command(s) and rollback,
you are sure that no changes to data are done, it is quite fundamental
to sql databases, you really do not mind to break it ?
etc.

Ivan