Yeah, you're pretty much going off the specs, as a determiner for what you actually need. There were a couple of threads awhile back about this stuff (as in "do specs really matter"?) I think it's a matter of actually comparing the various specs, in your field setting, to determine whether the higher specs are actually value-added, for you, or just for bragging rights on the NV forum.
Granted the newer stuff is pretty good, but the larger question is: does the stuff you now have work well for you, or is an upgrade really needed?
For example, I have 10-year old gen III -14's, which work really well for me in my particular application. So do I really need the upgrade? Probably not, especially with lots of other priorities.
But do I really want L3 Filmless WP goodness in my -14 housing? Fucking A skippy. If a rich uncle dies or something.