Thanks so much for your time and help with my lens question.

Hi Adrian,
It would almost be worth having two bodies:
One for the DA*300.
One for everything else.
The DA*300 is great. Pretty much any time I take it off the camera I regret it and it gets put back on. Everything I said in my review still holds. The performance is very consistent across the frame and across the aperture range. I find myself more and more often shooting wide open as I gain a greater appreciation of the wide open bokeh. It can be a little busy.
I am getting over the fact that it isn't quite as sharp as another lens that I own (Tamron 90 macro).
I still haven't tried it on a decent TC. I was hoping Pentax would bring out their weather sealed 1.4x but that doesn't look likely now. I really depend on that weather sealing and don't want to buy any more non-sealed lenses if I can help it.
A 420 mm (630 in the old format) f5.6 should be great for birds out in the open!

Hi Matthew - I notice you have the DA*300 and was wondering how it is going. I have one of these and a Kenko TC waiting at a friend's place in the US, so looking forward to getting them when I visit there in a month. Regards, Adrian