Do you really think he needs to jack his truck up 5 feet? It would probably roll if he did. 48" is more than enough!
While I can understand this way of thinking, I personally went with the 60". When I use my hi-lift, my truck is rarely level and on a smooth flat surface. If I'm stuck on an obstacle and need to pile rocks or wood under a tire to get out, where I place my hi-lift may be much lower than normal ride height.
In gaterose's example, what if the hi-lift point was 6-8" lower and you had to place rocks under the rear tire? I feel uneasy getting close to the top notches of any hi-lift since they do become unstable near the top.
T4runner13 - as you mentioned earlier, you plan on front and rear bumpers. The bumper's hi-lift points are higher than the sliders so the 48" may not work in all situations you may encounter offroad.
Regardless of which you choose, I suggest you pick up one of these for safety:
Hi-Lift Tubing Adapter
Photo courtesy of TRDParts4U.com:
As well as one of these:
Hi-Lift Base
Photo courtesy of Amazon.com:
I mounted the hi-lift on my roof rack using the crappy hi-lift tube mounts. I've been too lazy lately to design a better one.
Sorry to ramble on, I haven't been on here much lately. Hope this helps you in your decision making process.