Originally Posted by Gruoso 
Let us talk about real prices with the comparison of the OP (K20D vs 40D).
40D+Canon 70-200 f4 USM IS +Tokina 12-24+canon 50f1.8II+ Canon 300 f4 USM IS + Tokina 16-50 = 1100+1100+ 450+ 80+ 1200+ 650= 4580 USD
K20d+ Pentax 70-200 (ops, let us say 50-135 f2.8)+ Pentax 12-24+ Pentax FA50 f1.4+ Pentax 300 f4 + Pentax 16-50= 1300+800+650+200+1250+650= 4850 USD
Of course I am not considering other things such as the flexibility of the system, third party equipment.... I think that some people should start to explain its decissions in terms of preference rather than it terms of price. With the new offers, seems that Pentax is not a bargain anymore. It is no more (and no less) than an excellent system for those that make a given type of photography.
Btw Sven, this is nothing personal against you, I am just using your quote to make a point.
I just wonder why you would get the Canon 50/1.8 and not the 50/1.4 as a comparable one to the Pentax 50/1.4. The new Canon 50/1.4 would be around 350. That would put the Canon system in the same square with the Pentax's. Besides, the 40D is not really a direct competitor with the K20D, more like the Canon's 50D. At the moment, I think the Nikon D300 might make the valid comparison.
In the end of day, I have to agree that it's all in personal preference. If your studio shooting demands a good low light AF system, then either Canikon would be a better candidate. I would not hesitate to switch if the Pentax's becomes inadequate for my work. Fortunately for me, this is simply my hobby so I can get by with the slowness/incompetency of the AF system.