The silverbird actually sounded superb when I heard one about 4 or 5 years ago at Anthony Lomas's house (he is/was a Bohm demonstrator in the UK).
If they have kept up to date with any software updates/sounds then they will still be good in todays competitive market.
The sounds were rich and warm but some of the styles were quite lifeless comparing them to the likes of the Tyros 2, G70, SD1 etc.
I personally don't think Bohm is quite as advanced as Wersi are though.