Comes down to $$$
I've never set foot on a 240, let alone sailed one, but facts like that never keep me from holding forth an opinion!
I think you are correct in that the 240 tiller would impede some of the utility back there
under sail. On the other hand, at anchor or in the slip, you can spread out back that way. We lounge in the front area, mainly with our backs resting against the cabin bulkhead, legs extending aft, but sometimes stretching out athwart the companionway exit. The main sheet is occasionally an issue with crew seated in that area generally, but not that we've ever thought about it. Mostly, people sit on the high side, so the sheet is not in the way.
I believe there are a couple of owner-feedback improvements Hunter made when moving to the 24. If I'm not mistaken, that aft seat also is a locker, no? Assuming yes, that's a nice convenience. (We added a hatch back there to access that storage room, albeit less easily and less room than a locker.) There is a port facing into the cockpit from that dark area down below to improve with light & ventilation. (We added that same feature to our 23.5.)
Mainly I think it is a question of the $$$. They are similar to the point of being the same boat, IMHO. The 240 is likely to be in better condition merely due to its younger age, but that difference is beginning to fade away. We only looked at the 23.5s in fall '06 because the premium on the 240 was just too rich for us at the time.
However, I'll presume you have perused the thread nearby on upgrades to this class of Hunter. There is a suggestion that it is better to step up in $$$ to get a better appointed boat than to go cheap & upgrade yourself. There is merit to that position. Some of the best advice I ever got when shopping was: Buy the best boat you can for the money you have. Don't buy a beater thinking you'll save money because if you add up the time & expense of repair, you would have been better off buying a better boat to start... Plus you will have been on the water instead of on the hard!