I haven't heard of anybody knocking the oil filter, but I didn't like the position of it, so I (like other crd KJ owners I know) fitted a skid plate, which also protects the sump, autobox and transfer case.
Whilst the IFS makes for great road maners, I don't think I will be taking it offroad. The lack of ground clearance is noticible. A decent 2.5" suspension lift is £700 just for the springs and shocks, then add the price of tyres (31" max).
I will be trading it in for a long wheelbase wrangler when funds allow, although I have been glad of the permanent 4wd this winter (not available on the Wrangler).
Ivan