So, quick summary on the BCs.
Haven't driven it far yet, so hard to give a full review. So they're pretty hard

Not cripplingly hard, but certainly a lot stiffer than my ragged out Teins. At this point I reckon I'll leave the spring rates, but I could certainly recommend 6kg & 4kg. I reckon that'd be perfect for street use. This review is done with them at the softest damper setting too. I'd love to wind them up when I next get out to Wakefield.
Many of my phantom suspension noises have disappeared & they allow me to get much better traction on take-off. None of this bouncy cavitation rubbish I was getting before.
Installation was fairly straight forward. Finding the ride height was a bit fiddly though. I've set the gap between the lock rings to 120mm on the front, 112mm on the back & it's pretty much given me the same height as I had before, if not marginally higher, but imagine they will settle down with more driving. I'm still contemplating dropping them all further by one rotation.
So all in all, a thumbs up from Bennoz. Will get some pics up shortly.