I have to be honest and say that startup times, including ChoosePixelFormat is not an area that we've really spent a lot of time optimizing. We'll take a look and see if there's any obvious problems. We've been actively working on the shader compiler performance, though, and hopefully it's compilation speed should improve over the next little while.
The invalid shader binary issue is one we're aware of and have fixed recently. That fix should show up in a Catalyst release in the next month or so.
I sent the information about Cycles to our OpenCL team - they're going to take a look at it and see if we can't make it run well.
I'm glad you like our hardware. We're working on improving the drivers all the time. I think we're making good progress, but we need help from our users (like you) to make this happen. Thanks for the feedback. I'll post back here if we find any obvious solutions to the problems you've reported.
Thank you very much,
I hope to see results soon