Susan:
I first went down to the music store to buy a Yamaha P90, a digital piano. I'd played one before and was really impressed by how piano-like the keyboard was. It felt more like a real piano than any other digital piano I'd tried.
But after thinking about it I decided I couldn't justify a piano, I needed a more general-purpose synthesizer. The S90 is basically the P90 with a synth tacked on, so I went looking for that instead. Couldn't find one in town, though, so I gravitated toward the Motif, which features the same piano samples as the P90/S90.
But I didn't like the keyboard on the Motif nearly as much. Too synth-y, too plastic feeling compared to the P90. The music store guy suggested I look at the MO8, a new model at the time, that featured the same samples as the Motif but with the keyboard used in the P90/S90/P120 digital pianos. So I got one, and have loved it ever since. Great weighted piano feel, very comfortable for someone accustomed to acoustic pianos. Sounds good, too -- just like your Motif.
I saved nearly a thousand dollars, too, over the Motif. I spent that grand on a Kurzweil rack module, so I have polyphony galore without resorting to soft synths and their, uh, challenges.
I'm still on the hunt for a good organ-style keyboard, though. The downside of a piano-style keyboard is it's painful (literally) to play organ parts on. Got my heart set on the new Hammond XK-3c, but at $2300 the contents of my penny jar won't quite cover it yet.
EDIT:
To clarify, at least three different keyboards are used for the MO and Motif product lines. The 61- and 76-key versions of the Motif ES use a standard synth-style keyboard. The 61-key MO6 uses a semi-weighted keyboard. The 88-note versions, both the MO8 and the ES8, have hammer-action keys, possibly the same exact keyboard in both.