The 240 is mechanically very similar. I've owned a bunch of 240s, having moved into the 700/900 arena a while back also.

The 940 is definitely more plush as far as interior appointments go. The 240 is a little bit more brash than the 940 ride-wise, but the 240 does handle well. Both are excellent cars. They each have their respective weaknesses, but the 940 is perhaps slightly less problematic save for electronic options.

940s have standard ABS brakes, the 93 240 has those (and 92, 91 optional).

91-93 940s have driver airbag, 240 has that too. And the 93 240 has the best 240-series air conditioning, both in capacity and in ease/cost of repair.

There are a lot of bonuses to buying either one--if you're worried about a 240 being a "lesser" car, it isn't. A lot of it hinges on what you want to be surrounded by. Mechanically they'll be quite similar.
--
Chris Herbst, in Wisconsin.