IF ? your going to ride real slow there isnt much between them both have plus and minus the DR350 is a rugged steed and simple in its design the DRZ should have better ergos and better sus water cooling helps it stay reliable and produce more power weight wise not sure the diff the foot pegs would also offer a better purch for your slabs of meat ? the DRZ should be the better bike and more pleasing on the eye ? more modern and the DRZ400E would my choice
IF ? your going to ride real slow there isnt much between them both have plus and minus the DR350 is a rugged steed and simple in its design the DRZ should have better ergos and better sus water cooling helps it stay reliable and produce more power weight wise not sure the diff 
