it is too early to give here the correct advise. The specs of the K20 are looking really very interesting. As you can see with the K10D already, Pentax is able to offer really interesting solutions.
But before doing a system switch, I would thing also about all other aspects of each system. Also Canon will brig new mdels on to the market this year.
So my advice would be to wait until you have more infomation about the K20D and at the same time to think about pro and cons of each system (Pentax vs. Canon). There is none, which is for everybody the bets. It depends always on what you wnat to shoot and your personal preferences regarding handling, specific lenses you need etc.
I know this thread is only 12 years old but I switched to Canon. Bought the 40D and the 24-105. In the end I had a 5DMK3 and very nice professional lenses. About 10K of equipment. Than I needed the money and sold everything some 7 years ago. And later I thought what to do now? I'm no professional. So I came back to Pentax. Shooting a K70 now with the 18-135 and the 50MM. Plus the Fuji X100S that I bought new in 2013. Very happy now and saves a lot of money. And my images are as good as ever.