My setup: + Works perfectly. All thrusts are on my left hand, so tri-chording is easy/natural, and the stick works for all the rotations and weapons.-------------There are lots of different control configs. The best ones allow you to easily maneuver in any combination of directions + use weapons, without straining or changing your finger placement.Also, remember that anytime you change your configuration, it will take a while to get used to.
You are not going to improve with just the keyboard. It is 99% impossible to get enough control to move in all 6 axises at once and do the other things while getting shot at. The stress is too much and the clutter and reach is absurd.
I can't even imagine trying to play with only a keyboard.
I used to try it in the D1/D2 days. I could never get very far with it. Level 6 in D1 was nigh-impossible, and the first boss was very hard to do without getting blown up by the smart blobs left and right.