One thing to bear in mind with having the wheels at the front is that there is a possibility that the robot may veer or spin slightly when you try to go forwards. Quite often when you have drive wheels at the rear of a robot, going forward in a straight line is no problem but when trying to reverse in a straight line, the robot is prone to spinning round one of the wheel axis' (Drumroll was particularly bad for this - watch some old Youtube vids and you'll see it very rarely goes back in a straight line, I always had to sort of wiggle it backwards)

If you have the wheels at the front, you've effectively got a rear-wheel-drive robot going in reverse, so the robot could suffer from this issue, although the effect may be less if the weight is distributed evenly as you are planning to do. There is some physics-related explanation as to why a robot is generally easier to control when the wheels are at the back but I'm not even going to pretend that I remember what it is. It made sense though when I heard it.

Avenger (the Aussie axe) had its wheels at the front too when it was first built, with the idea that it was easier to point the axe at an opponent, but the builder moved them to the rear when it got rebuilt as he was struggling for good straight-line control.

Obviously each setup has its pros and cons but they're just some points to consider when deciding.