I don't find the 599 compelling at all. But to each their own.
Rotax is making the 800 twins for BMW for the F series. The F800S/ST guys aren't really a happy lot - a fair amount of teething pains with the platform. I think that BMW has held off on releasing the F800GS so that they could sell the F650GS bikes. Those can be had on the used market pretty cheap. New BMWs are pretty spendy, and a number of people complain about not really getting a premium quality bike for the money.
I do find this compelling though
