The reason the cost for C4 didn't double when the cost for a tank is very simple. Light Assaults are not using a force modifier (neither are medics/HAs/engies), they're simply using a utility. The utility is haphazard at best, and exceedingly costly given that it has a finite amount of damage it can do. The absolute best case scenario is using 2 C4 for 200 resources and killing two tanks+4 occupants, if those tanks are immediately adjacent to one and other. That means 500*2+300*4 xp if ALL of them are extreme menaces. Oh, and 10xp for the group kill. So 2210xp. 1100xp in a more reasonable situation, IF you're successful. 0xp if you're not. For 450 vehicle resources, you MIGHT die to 200 resources spent on C4. You might die to 0 resources spend on rockets (why does no one complain about this? It takes -far- less risk than C4. Oh, because it's less annoying, and they've more chance of getting the kill whilst still not having to pay attention). But, for that 450 resources, you put yourself in what is essentially a 3* force multiplier (3 times higher score per hour, last time I checked, anyway). In fact, it's more than that because your gunner gets a 2.something force multiplier too. Rather than having a finite potential earning, as with C4 (or tank mines, AV grenades etc etc), or the potential that your resource investment does not increase your power (grenades miss, C4 doesn't detonate, mines get avoided. Tank shell replaces your main gun; if you don't hit, that's only the same as missing with your carbine/RL. Tank armour replaces your health; anything that would kill your tank would have killed your inf.), you -become- your resource investment, and in return, it amplifies your score. An 'average' LA will earn 7-10kxp/hour. This is tripled to ~30k/hour in an MBT. If you only make the MBT survive for 6 minutes, rather than earning 1kxp, you'll earn 3kxp. If, on the other hand, you make your MBT survive for 30 minutes (the battle for what, 2 bases? maybe none during high pop), you'll earn 15kxp instead of 5kxp. So for 450 resources, you're making 10kxp, vs a maximum of 5.5kxp for the same amount of infantry resources (and a FAR more likely number around the 1-2k mark). TL;DR: Stop trying to argue for costs based upon what kills what, and start realising that costs need to be relative to what something achieves on average, not what it might achieve under perfect circumstances. If spending 100 resources on a MAX nets an average player 20kxp, whilst 100 resources on C4 nets them 500xp, there's a problem. If spending 200 resources on C4 nets an average player 10kxp whilst spending 400 on a tank nets them 1kxp, there's a problem. The former was the case. The latter has never been, and isn't the case.