Can't blame the camera guy for his view, after all, he's interested in selling cameras. Canon and Nikon are the "safe" choices for him as they are readily available and make nice cameras. At least he was honest in his appraisal of Pentax capabilities.
However, Pentax (to me) is a much better value. I'm one that rarely shops in a B&M as I can do all the research I want online and then find it at a better price. Ergonomics is nice, but I find that all new cameras feel strange at first until I get used to them and how they work. I suppose if a camera really bugged me, I'd return it for a different one, but I think it's more a case of me getting used to the feel. Therefore I don't worry about buying sight unseen online.
As for availability of Pentax gear, all I have to do is give the magic computing engine my credit card number and a nice man drops it off at my front door a few days later. How much easier can it be?
BTW - congrats on your purchase. The K20D is a very nice camera and you'll have a lot of fun learning all about it.