I've read here, and on other posts, how great the 700/900 cars compared to the 240. And you've got good objective arguments, e.g., SIPPs and side-impact protection, as well as a subjective one (e.g., the ride is smoother).

But the thing that keeps me and my wife in 240's is the seating! With the seats adjusted to their highest level, we're able to sit bolt upright, like in our SUV (which we only use to pull our largest boat, beyond the 240's rating). Unfortunately, in the 700/900 cars, we feel like we're sitting on the pavement -- we've tried them out, and they're just too low, and too reclined! Sure, not as low as many other cars, but not as upright as 240s. For a few years, we even had a couple of M-B's (300E), but that, too, was too low, and I found I had a stiff back after a long drive. I can drive all day in my 240s and step out and feel great (well, good) -- couldn't say that about my 300E's (which I finally sold off).