OK, so I didn't get around to posting an update on the P6 immediately as I thought. That's possibly a good thing really as it's better to give a new piece of hardware more time to establish itself in the setup. Especially with a controller keyboard like this, which has fundamentally changed my workflow.
All in all, the P6 is settling into its role well and although the keyboard doesn't have the best feel overall it is a compromise between a piano and a synth feel. I'm certainly not using the controller to its full potential but I'm gradually using it more and more as time goes by. I'm not a big synth sound tweaker but I have found the tactile filter/envelope control really nice, resulting in me tweaking sounds a bit more.
The transport controls are excellent and I'm finding these great and I use these more often than not. I also now very rarely use a mouse for fader and pan movements, with the motorised fader and the small mixer sliders getting a lot of use. With the latching when the current channel volume is reached it's really usable.
I can understand the few criticisms I read before purchasing the P6 and I was, and am still, not entirely convinced with the look and feel of it. But, for me, I can't see any other controller offering the same level of flexibility of control. I'm using the mouse a lot less for tracking and general mix operations now. I have experienced the occasional glitchy connections but its never been a deal-breaker.