Great you asked
Seaball
Well simply from my one weekend experience with both motors... geared properly and having two different drivers try either motor it was apparent that the KD was simply faster. Yes the CP look to have more pull but, also stated here, it flattens out. Were as the KD had about 2-3 more car lengths to it before it topped off.
I guess its all application that applies here however if you can gear the car appropriately to the track either one will do however the KD in my opinion will have a larger power band to work with I feel.
Lastly, gearing them improperly, they both will burn up fast and they are touchy with the right gearing. Also, brushes for the KD are easier to come by and are relatively cheaper. Yes, you could last longer with CP however back to the improper gearing that's a big cut in a wallet to take a chance at not only that if you don't notice it at first imagine the damage.
Personally, I have the KD. I've told a fellow pit mate to try the CP and he enjoys it... So my first poser was my choice by ultimately its really personal preference.
GL
And remember to temp it and make sure its around 180 for both motors too cool or hot you're not getting the most out of it.
I believe the KD likes a 6.1 FDR and a CP 5.89. Cheers!
Rudy