I got mine on sale and really like it so far. I'm a tapered shaft guy in general, but this is one of the nicer ones. I like it better than my Synthesis and Synergy II shaft, would likely place it ahead of my Inno/Dolo tapered shafts, but it's still behind the R2 Xn10 in my opinion. I like the RBK grip and the handle shape. Decent kick, but not incredible.
I've used the tapered rbk 6k senior shaft (mid flex) with a synergy II blade for about 2 seasons now.
Replaced the blade once - and the Shaft is a bit chipped up now, but it's lasted longer then I'd hoped for orginally - love the stick / blade combo.
I'm heading to the states soon, and will be looking for a new shaft - maybe the 6k again depending on what deals I find.