My civvie version leaked but I never really noticed it much until recently.
Doing a Farmer's Market in the snow with my boss he asked if I'd put a wee nip of whisky in our coffee, brewed on the SAT. "No, it's probably meths" - which he confirmed with dirty looks and foul language. Oops...
I've never had the military one leak and never noticed them being slower. The brew goes on and its ready when its ready - it was a different matter when I was a squaddie though!
Maybe the real difference is that the military burner is meant to be squaddie/bomb proof?
Liam