I currently have 2 cars on the driveway 75 cdt conn se and a mx5 for the clear days and like Nigel I have hardly touched the convertible... I know the 75 aint a 260 but its such a nice drive and as its been suped up its very responsive. So I decide to get rid of the mx5 and go for a 260 (Thankfully the mx5 is staying in the family so I will still get some use in the summer) Hmm I should not talk you out of selling the 260 especially Nigel as I am after buying one......
Worse case scenario is you sell it you discover you miss it and then go out and buy another one in a few months when they are slightly cheaper (cant see them going up but you never know)