Military resource - any real benefit?

Yes.
Try this test:

Make a custom map and place a few mil resources near your home planet.

Start a new game and use the cheats to give yourself all the techs.

Build a warship and launch it, be sure and note its attack and defense values.

Use the cheats again to send a bunch of constructors to grab the mil resources and upgrade their mining levels to the max in one turn.

Now end the turn and then re-check the ship.

It should have gained a bit of an advantage in attack and defense...

If you can't figure out how to make a custom map (Guilty here), just mine a military resource and then watch your weapon and defense bonuses rise with it in the empire manager window.

Is their a tool or program used to make custom maps?

Anyway, these resources give a significant advantage in ship attack and defense which is like being significantly farther in the military tech trees then you actually are. Also it's cheaper to build in imposing military so people don't go to war with you.

@Zerogman

The tool to make maps is GC2Builder, you can get it at gc2builder.com

you can also just look at the "stats" section to see your offense and defense bonuses. then add up the total of what your offenses and defenses should be, and compare it to what they actually are on the map. unless both are pretty low, the ship builder should show much lower values for your ship.

the % being mined gives a direct boost to your attack and defence. I think maxxed out the % is around 50%. (42% i think exactly).
This means a ship you build with 100 attack now has an attack of 150 (142 not rounded) which dominates.

It will become significant if you use ships with high attack/defense values. If you are running around with attack 1 or 2 ships it won't matter. Once you hit 10+ it should start to show up.

If your going for military conquest, this is the best resource to have, had one maxed out at 49% playing the Drath. Had defense of over 100%, my ships in combat rarely took a hp in damage. They were invincible in combat even though the other races were 3-4 steps ahead in the weapons tech tree. 30 missile defense was 60+ missile defense, great...

Access to military resources will often dictate how aggressive I am. If I have a couple of them I will take a more conquest oriented strategy.

In one freak game I played I started with 4 of them (no other resources, just military) on a huge map. I actually quit that game before completing because it had made my ships unbeatable. Not much of a challenge, but fun to watch your small ships slaughtering a squadron of battleships with no losses.