In general, I find jumping much easier with a controller. I have not tried the PC version of D2:ED, but playing Psychonauts on PC I started off with the keyboard and mouse controls, but then had to switch to a gamepad for anything requiring much coordination.
On the Xbox the shoulder buttons are used to switch between tabs in merchant inventories, the quest log, etc. When paused (right stick button), hitting a shoulder button brings up a menu where you can select potions, items or skills to use, without needing to assign them to a button (and for potions/items a little more convenient than going through the inventory menu).
The left/right triggers are for target lock and jumping, as you have them assigned.
The first, cheap (gameport
) gamepad I ever got (to play a freeware game, no less) had 4 buttons and a D pad. Two of the buttons were 'repeat' functions of the A and B buttons, so holding down the RA/RB buttons were the same as repeatedly mashing the A/B buttons. I have not seen that in any recent gamepads (haven't been looking actively), but it would have come in handy a couple times (that function may be able to be replicated with gamepads that have macro buttons).
