I really think someone ought to talk Sir MB into adding some extra aircraft to the bmibaby fleet, because unlike the case with Air Canada, whose low cost airline zip is restricted to 20 Boeing 737-200s by unions, it doesnt seem to be a problem to expand the airline.
To try and stretch 13 aircraft across 4 bases and to try and consider the airline as a growing and major low-cost-airline is just plane stupid.
I would say to let it have at least 20, and to standardise on the -300 series.