The fact that if it's raining when I get out of bed, it'll take me ten minutes to put the hood up, pushing in all the poppers etc. The Caterham would be a weekend-only option really, rather than one that needs to be relied upon for commuting also.
Then leave the roof on at this time of the year.
If you want a true and fun drivers car, there is no other choice than a 7-Type vehicle or an Elise/VX220.
I was under the impression that it would be used for the very short commute only occasionally?