Get rid of that bumper will probably shorten the front approach 4-5" then you'd gain more by not having the bumper 2-3" below the frame.
The bumper does hit once in a while but it's not too bad now that it has been chopped:
Before the cutting, it did hinder approaches pretty often, hitting on the outer tips of the lower tubes.
Now it mostly it gets hit on the underside of the leaf springs. An SOA would allow bigger rocks to slip under there, allowing the tire to contact the rock first. But the downside is that the rock could also hit the tie rod first if left in the stock position.