I think your requirements of low light fast AF capability and high performance of high ISO speeds are both not strong points of the current Pentax AF bodies. As you have stated, the Nikon D90 excels in both far beyond what our Pentax DSLRs would do.
The good thing I would let you know is Pentax seems to have found out a way to improve their sluggish AF performance at indoor and dimmer environment with their K-m (whilst the K20D is still of an older generation of the AF system), see this and you will know:-
RiceHigh's Pentax Blog: AF Speed Difference of K-m Vs K20D
So, I suggest you if you do not have urgent needs, just wait until early March to see what new stuff Pentax will offer to replace the K20D and the K200D (
which was discontinued already). If you cannot wait, you could start a new Nikon system first and to run two systems concurrently before you can decide further which system you like more and suit more your shooting needs.
I have got and used a Canon 5D for almost two years now but I still have not abandoned my Pentax system. In fact, I have almost not used my Pentax DSLR body anymore. I think
this would be the last time I used my K body. However,
I still use much of my excellent Pentax glass daily and more than my Canon glass (including a L lens), on my 5D.
YMMV, though. In short, run in dual if needed. But frankly, for most people, I can't see the need to invest dual systems unless you have special requirements or specific needs.
Originally posted by lapeen My best friend recently got a nikon d90 and I am in love. She is able to get so many shots that I could never get with my k100d. I had been feeling frustrated and limited with my camera even before she got the d90 as my daughter has become a cheerleader and my camera REALLY struggles in the low/crappy light of school auditoriums and I have to either accept a lot of grain or motion blur.
Examples Our family and friends also do a lot of evening activities and hanging out and the d90 captures those moments with ease. Last night she had her ISO at 2000 and the pics were bright and crisp and not at all grainy.
And I know that it's gimmicky and a bit of a controversial "issue" ...but it was pretty fun last night to be able to snap great photos, and then when someone was attempting to dance like Beyonce, be able to switch over to video and take a little movie
The movie thing is NOT a deal breaker for me... but it is kind of fun!
I pondered going for the k20d so that I could keep my lenses... and I do love being a Pentaxian, but I have been told that the k20d won't make me happy and do what I want it to either. Looking at the
ISO tests on DPreview and other sites seems to confirm this.
I know that none of us have crystal balls... but as I am no urgent rush to get new gear, do you think I should wait awhile and hope that Pentax comes out with a camera that makes me squeal