I've not owned an Elise 250 but I have owned an S1 Elise, and S2 Exige and a series 2 Europa, the latter being very much maligned but when set up properly probably the best of the lot. Putting aside performance if you are looking at useability the Caterham is no better or worse than any of the Lotus cars. With the roof on, the Elise is much harder to get in an out of, not just because of the entry slot but also the Elise has a very deep sill that you have to get over. Linked to this, I think the Caterham with the hood off is a much nicer place than any Elise variant with the hood or roof on. I have never used a hood of an sort on my Caterham, but in an Elise with the hood on there is not much headroom and with the engine behind you it can get very noisy, plus they steam up a lot in the winter! I love all the Elise variant cars and if I had garage space would have another S1 in an instant. But, if useability is why its being considered then think really carefully as you may not get what you want in terms of comfort etc and for a pure driving experience the Caterham is better. Have you considered a Boxster or a Cayman? Not quite a pure as a Lotus, but not far off, but much more useable day to day.