Hi Anthony, I would stay away from the Primavera 50. It's really only designed for places in Europe where you don't need a license for small capacity machines. It would be fine when taking back streets to the local shops. However its always much safer to be able to ride at the same speed as the traffic around you than to be holding up traffic behind you, especially as Melbourne drivers are so aggressive. So yes, it would be very underpowered. The Primavera actually has the same sized body and wheelbase as your Sprint. However it has 11" tyres instead of 12" tyres. This lowers the seat height but not by much. Only 10.16 mm. I'm sure you enjoy the punch of your Sprint which means you can easily take it on long rides, even ones that are very far from the city, hence another Sprint would be a far more versatile choice. Some club members who own modern autos have had their seats cut down. Otherwise search outside the world of Vespa for an auto scooter which has a much lower seat height. Best wishes, David
Thanks Anthony. Yes, practice is everything. Once your wife starts to bond with your 150, then that's a fine excuse for you to look at a 300 :-)
I totally agree with David's comments. Having ridden a 50cc it was the scariest ride I have ever done in the city...it was a loan bike while my GTS 300 was being serviced at Vespa House...LOL. We have quite a few ladies who are no taller than your wife who ride the Primavera's and yes you can have the seat shaved down if necessary... getting used to the weight of the bike all comes with practice and I am sure in no time you and your wife will be out riding together and enjoying yourselves.