I purchased a Ketron SD7 a few months ago and can honestly say I have been blown away by the whole keyboard. It is such a lovely board to play.
In the whole time I have owned it I have had only one lockup and at the time I had been doing a lot of file copying and pasting (Henni's files from this site). After I finished the copying I went to play a style and it locked. I can live with that, no problem.
I also own a Tyros 5 and if I was told I could only keep one board, it would be the SD7. The styles seem to have much more in them than the yamaha and the voices to me sound a lot better especially the saxes and clarinet. I am not a lover of the super articulation voices on the Tyros as you can get some strange results but that is probably the way I play.

May I just say a very big thankyou to Henni for the huge collection of Ketron styles on this site.

I have no intention of selling the Tyros, it's still an amazing keyboard and luckily I can keep both.

Alan