I haven't tested this with Xbox controlled but based on your description I assume the triggers show as both buttons and axes.
For each movement you can bind one digital and one analog input, so now that you have mapped the LB/RB as digital roll inputs, you should remove the RT/LT analog bindinds. But having said that, I realized there is no way to remove a binding, other that binding that input somewhere else.
While trying this myself I found another issue: When reassigning one analog axis direction it removes previous bindings to both directions :|
I'm happy to hear you liked some of the changes :D I will address these binding issues in a maintenance update sometime soon..
BTW, that start-up sound IS the sound of an old hard drive starting with a bit of other stuff mixed into it.