I just picked up a used one a few weeks ago, and quite like it. I like the action--not too heavy and not too light. It's not the best action I've ever played, but not bad at all. I mainly picked it because it has breath controller and ribbon controller inputs. The onboard sounds you'll probably never use due to how far we've come with software based products in the last several years, but if you do use any, they're certainly useable--far better than a lot of ROMpler crap out there like Steinberg's Hypersonic.
There are always some available on ebay, and going for really good prices, so I think it's great bang for the buck. You could certainly do a lot worse with some of that M-Audio crap.
I finished up getting one 3 days ago and it came with a crapped keyboard. But the supplier who turned out to be very good and professional had it replaced within 24 hours. I will use them again.
The action is as you describe - I can't add anymore except to agree. Nice action and not as heavy as an S90 ES. The main piano sound is slightly different to the Yamaha - but very good. You can practice on that sound forever. In the end it's just for a project and as a controller.
The onboard sounds are OK - I use them all the time actually for sketch type purposes. Also - I can't be bothered to turn on computers until I get something to work with and the sounds on these instruments, while making tech sample heads poo-poo, can influence many things and moods and are very playable.
Sample heads need to understand that I'm 50 times better at playing a keyboard than they will ever be in their dreams.