I actually find Heavy Gear with its extreme efficiency internal combustion engines and various fuel-cell/battery schemes more plausible on many levels. Having the biggest weapon on the mecha be the engine leads to some really awful strategic realities. And that's not even counting when you are on defense and really don't want to trash the local landscape.
My reluctance comes partially from a discussion of piracy in a star-travel setting. How do you go about robbing people who are sitting on a massive matter/anti-matter bomb? You can't easily threaten their lives because they absolutely have the means of taking you with them.
The spoilsport feature allows you to get the last laugh and will probably include a nice deliberate ammo cook-off in its function, but for now I'm leaving catastrophic self-immolation out of the base rules