I've spoken to an ADF chap I know who's used the F90 GBBR, first time i heard about it was about 8 months before it was announced to the world as he's been using them for the past few years.
I didn't believe him to begin with...
He says its great fun and wishes airsoft was legal there.
Genuinely cannot wait to get one, it will Tee off my AUSTEYR and ADF collection nicely.