Hall sensors and CPS are not compatible, but I don't think having both and using only one (with the computer it's designed for) would cause any problem. The Hall-sensor/CPS change had nothing to do with the different car models, but rather with the switch from LH 2.2 to 2.4 (and later Regina). LH 2.2 has a Hall sensor on the dizzy (either rear mounted in a 740 or side mounted in a 240) while 2.4 and Regina have a CPS. But I think if you used a dizzy with a Hall sensor in a later car it would work fine, you just wouldn't connect anything to sensor.

What I have heard about the relative benefits is that the rear mounted dizzy is better because it is a direct connection to the cam rather than having to be linked to it via gears.
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Andy in St. Paul - '91 745 227K mi, '91 745 210K, '90 744 194K, all Rex-Regina; '86 745 GLE M46 230K; past 240s