As others have mentioned, the K110/100D does well using high ISOs. Add to that in-body SR, and you're practically covered for most types of photography.
Of course, if you're looking to shoot a lot of sports, that buffer might be too limiting for you. Then again, I've seen people using the K110/100D for sports photography, and they've gotten some remarkable shots.
It's up to you, really. I was also in the same quandary as you. I ended up with Pentax, just because of SR (consider the cost of IS and VR lenses versus non-stabilized ones), image quality, and the availability of cheap old glass (which works well on Pentax DSLRs, I might add). I'd suggest you look over at KEH, eBay, or some other used lens store and see if the choices are to your liking. One of Pentax's greatest strengths is glass, from the Limiteds, to the *'s to even the humble 50's.
As well, I love the brightness in the viewfinder of Pentax. The 400D's was small compared to the K110/100D's.
Try them out for yourself at a store. You wouldn't really appreciate the differences until you try the cameras out yourself. Good luck!