I agree with Targ - although in Ireland there will be no requirement for a "type rating for a 4 seatrr": just a bit of training - typically an hour or two as a new PPL, to switch to a new type. Just enough to get you and your instructor happy.
I have plenty of hours on both, and whilst I prefer the PA28 for touring, regard the C150 as a better training aeroplane for all the reasons Targ says plus a door both sides and simpler cockpit.
G