I think I should really decide now before I get too far in to the project. There are a few things that I have to weigh up really...
The pros of using the UDK are not only visual. The work-flow is much quicker in the UDK, they bring out updated versions every month with extra little tweaks saving previous click time. There is also a large community of UDK users right now which I can depend on when, and I do mean when, I run into trouble. Theres also the lighting system in UDK that brings life to maps. Now, you could argue that lighting has little impact on game play, but I would argue otherwise. Lighting can bring an environment to life and with the Lightmass feature of the UDK it brings a fantastic realism with soft bouncing light.
However, the main reason I'm tempted to use the UT3 engine is for game play purposes! This is what this engine was built for. It includes all the weapons, pick-ups and bots a designer needs to create a class Unreal DM game whereas the UDK features a mere 3 weapons and 1 bot with a selection of the core pick-ups used.
If UT3 is the forgotten middle child screaming for attention, UDK is the experimental new baby of the Unreal 3 engine which allows users to customise the hell out of their projects so that the projects no longer look like Unreal workhorses are driving the game. After all, did I not want a distinct visual style? Was that not one of my criteria? I feel for game plays sake I may have to compromise on this.
I'll sleep on it but for now heres a test shot I did in UT3!
...Although not the new born child with the fat cheeks, I think the middle child still has its charm wouldnt you say?