Ok, I know 5 lug is stronger but has there been a difference at all with 4 lug? Going with superior 4 lug 31 spline axles & a tru-trac eaton diff with 3.55's.
There's a local Fox running 10 flats with slicks and he's running 4 bolt axles and a c-clip eliminator. I think as long as you have good axles, you'll be fine.
The 5-lug bolt pattern itself at the wheel end is stronger (assuming you're actually making enough power to sheer off the bolts...which I doubt), but at the axle end...31-spline, is 31-spline.