Hello Mike,
I have bought a mainsail from Kemp and three headsails from P&K, including an asymmetric spinnaker, and got very good service from both of them. For the a-spin specifically, this question has been discussed before and it's worth reading this old thread, particularly with regard to P&K's specific design for the boat: http://parkerseal.org.uk/forum/default.aspx?g=posts&t=320&p=2
As always, of course, it's essential to take measurements and check them with the sailmaker, as that thread illustrates.
If you're considering a snuffer too, I recommend getting its lines made long enough to run to the end of the bowsprit and then back to the cockpit (described on here in another thread).
Have fun with it!
Anthony Russell
235/02 Sea Wyche