Scott and Others,
For ease of use and moving around to different editing pages and displays, the Tyros I find to be much easier to work with. The sounds of both the SD1 and the Tyros become personal tastes. In my store I think it seems to be divided right down the middle. Some really like one catagory better on one and others on the other. For sequencing I prefer the Tyros, but for the feel of the keyboard and size I like the 76 key SD1plus. Polyphony doesn't seem to be an issue with any of my customers because over the years of the SD1 I haven't had any complaints. I've only had 1 Tyros that needed to be exchanged because of a defect and I've had to have many SD1s sent in for display problems. However, the problem seems to be gone on the SD1plus and even when there have been problems, Ketron USA has been there for their customers to get the display problem fixed quickly.
Like Dan, I like the ability to turn off drum sounds quickly on the SD1 but both have the ability to use the drum remix feature where you play a midi file and use one of the internal styles for the drum track.
You can't go wrong with either keyboard in my opinion.
George Kaye
Kaye's Music Scene
Reseda, California