I'm 23, 6 years no claims and pay £550 on my Mk1 180. Not bad...
To be honest if you can afford the 180 I'd go for that. You know what'll happen otherwise, you'll be sat at the lights in your 120 and along comes a 180 beside you, the lights change, and you're left with the roar of a V6 and the tail end of a 180 disappearing into the distance.........
(Runs away and awaits a flaming...)