Is a Suzuki s50 a 50cc bike ?
Are you suggesting you want to go from a 50cc to a 900+ cc bike in one straight leap ?
If the bike is something else that I dont recognise then the ST2 is the simplest of the ST series but if you want a cheap commuter bike the a Ducati is not really goint to fit the bill as far as I am concerned.
"The Grey Assassin" - 2005 ST4s
Goldvalves , Re-sprung rear Ohlins , Tapered headrace bearings , Galfer Front Discs , Open airbox with K&N filter , Iridium NGK's with Magnecor Leads , 15/42T Cogs , Helibars with Oxford heated grips , HID Lights , CRG 'Stubby' Levers , Zero Gravity DB Dark Screen , Twin-Tone Fiamm Horns plus a bunch of 'detailing' modifications.