For me, Ian, the buttons are very handy. Once you get used to them, they are second nature. The sliders are the same way. The whole idea is to have everything at your fingertips rather than pushing through levels to get to the parameter you need while playing.
Thanks Bernie...I remember having a Yamaha PSR-70 (remember that old one?) that had switches in the same place, and they were very handy, and didn't interfere...and yes, sliders are good!
Ian