The ARB has been redesigned and is definitely not weak in any manner anymore.
I was part of a recent discussion on a 4x4 board regarding the failure rate of Detroits when an axleshaft goes.
The ARB is Competition tested and I've seen maybe one or two fail in those conditions over the last 7 years, so even before the redo, it was a strong son of a gun. The most common problem in the old ones was that the copper line would get installed incorrectly and would develop a leak. And the ARB got the nickname ARB Air Leaker from that.
I would NEVER put a spool in the front of a vehicle that has to turn. Hell, I'll barely put one in the rear (it will push or drag you even with the rear end disengaged!).
That said, the Detroit or ARB are both very good choices. Since it's a GM axle, upgrading to the D70 outers (35 spline) is as easy as just replacing the hubs, bearings and stubs. Then you can go a little less expensive and get the Alloy USA or Yukon joints to upgrade that weak link. If you don't upgrade the joints, at least get real Spice joints and not the el cheapo parts house ones.
Heck... I'll sell you my front Detroit for a great price. I have two of them sitting in my Rockcrushers that I want to go with ARB's (just because I want to). They're attached to 5. 38's so I know they'll mate to your gears, as you said you think you're in the 5's. It's for a 35 spline, too... since all front 60's are 35 spline
