There is something not right if you are using something else. Navy VR and USAF commercial derivative aircraft (C-40, C-37, etc) are using Jepp FD Pro like their Part 121 counterparts....
Chuck, you have to have the device to run it on. That's where the expense is. Not every command can procure iPads, and technically, you're not supposed to be using personally owned ones. Also technically, in some aircraft, even issued ones were supposed to be in Faraday bags along with your phone. Not sure if that's still a rule (on paper, anyway).
This also extends to the Part 121 and 135 world. You can't just whip out your personal iPad (legally) to navigate while operating under a company's certificate. Obviously the specifics of this are hammered out in the OPSPECS.
Wait, what? You guys don't have the standard Jepp/Garmin worldwide database package? I thought it was DOD wide. Interesting.
I know you have slides and everything, but the other thing to understand is waypoint availability vs aircraft capability. While "everyone" has DAFIF available to them in JMPS, that doesn't mean every aircraft is capable of loading all of those waypoints (as mentioned by Roger_Waveoff). And that capability changes over time.
Why is this? Two basic reasons...1) computer power (RAM and processing speed) and 2) being hamstrung by the various contractors because the Navy accepted buying products that had proprietary code.
#1 is an on-going upgrade process tied to funding. As an example, I think it wasn't until Gen 5 computers that MH-60 got moving maps (the Sierra may have had it before that...I can't remember...but Romeo needed the extra power to do some other fancy stuffy on the mission side).
#2 was historically a big deal for both Super Hornet and MH-60. That was supposed to be in the process of being fixed but I'm not sure where that stands at this point. Trying to get something added that wasn't initially contracted would usually require paying extra money to LockMart, although there have been exceptions (Romeo HUD, for example).