lmfoa... we at 7DS had this conversation and it came down to someone RP'ing a TEC Fleet Commander yelling, "We need Flak Burst against those fighters. All hands deposit small bills and change to the hopper!"
Credits to activate abilities is just silly. Metal/Crystal I endorse fully. But honestly, who in the hell wants to get pwnd because your ship's atm was dry and you couldn't activate Missile Barrage?
LMAO!!!!!!!!!!!!!! SWEET RESPONSE! Nicely put! Just love the 'All hands deposit small bills and change to the hopperAll hands deposit small bills and change to the hopper' ! It's killing me right now!!!! *I'm bent in two laughing!!!
Secondly,
I think a nice variant of that would be to have ships and structures that can create antimatter, if they're in your fleet (or if you're in a grav well with an Antimatter creating structure, then your antimatter will refill faster or slower, depending on the number of structure/antimatter creating ships avaialble. A side effect would be that when those ships or structures are destroyed they cause area effect damage to all within a certain radius.
I am currently implementing this in my Nephil mod, my dear friend!
I have 5 utility ships to begin with!
*Tanker (boost turn and ship speed) but becomes neutral and explodes for massive AoE when it is destroyed,
*Supplier (reduces ability cost, decreases antimatter cost),
*recycler (gain a percentage of ressources everything ANY ship in the gravity well is destroyed,
*Gerellion (a mobile ship factory) which has the repair ship ability
*and finally, last but not least, The Backstabber, A medium range artillery gun capable of firing 4 times before becoming obsolete (though the shots it fires are shield piercing 
(Awesome disposable little toy before you say hello to an enemies fleet or homeworld! 
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