Thank you both for your great responses! What little I have played it, the keyboard feels pretty good. The keys are tight, not wobbly, and it seems to respond pretty well to pressure. It sounds like it will be worthwhile for me to explore it further.
MisterHemi, I'll take you up on the offer of answering questions. I appreciate it. It will be a little while before I can dig into it as I will be out of town on business the next couple of weeks. I get what you are saying about being lost without the SQ-80. I have a 13 year old Yamaha S-90 which is a fantastic keyboard for me. The keyboard action is the best I have found on any synth. I even prefer it to the new Montage. When it dies I will be heartbroken! But so far, it has remained in excellent health.
Other than a few scratches, it seems like the synth had very little use. Now that I know it will be a worthwhile adventure, I'm looking forward to learning the instrument!