Hi from one of the whoevers. It seems to me that recreating the functionality of the current DBI is goal #1, no matter what other goals might be in mind. It also seems to me that an attempt to create an Ur-SQL, while noble and worthwhile, is a separate enterprise that should be accomplished with extensions to the core, but that's just my uneducated $0.02 as I haven't yet had time to investigate your Rosetta project.
I am pretty sure that we are going to be trying to get the PDBI as close to what you are used to as humanly possible. Where people suggest features and they get accepted on their merits I am sure Tim will try and get them in although I think they will probably go through the mill before they get accepted as features to an already stirling product.
Harry