DonM,
Perhaps we just got too used to the sounds and both needed a change
The SD1 absolutely still belongs to the best and keep in mind it was released about 5 years ago (!)

Navigating on the SD1 is complex and sometimes hard to understand. (I'm an IT-guy!)
It took me a couple of months before I found the use/meaning of 'block-registrations'.

What I do like on the Tyros:
One touch setting
Data entry wheel
Wonderfull display
Excellent strings, brass, epianos, guitars, organs, orchestral-drums...etc.
Noise-less harddisk
Panel layout (ergonomical)
No latency and polyphony-dropouts

"Fast action ready"