D20 SRD without HP is pretty fun. I didn't have a game to test it out, just a little of scenarios and statistics about the lethality of the game. I stumbled on my D20 Fading suns book (3.0 DnD) and checked out of curiosity how many of my homebrew rules applied. It also appears to work fine without hit points.
In fact I find the game more enjoyable with the lethality. A sword blow or a gunshot able to kill a character, regardless of power level is grounding. If you wonder "How do I avoid killed" the simple answer is "Avoid Violence" . There are so many other resources and means to overcome challenges and obstacles. Its an RPG game, there is "no right answer" I'll run with what you've got or I'll help you collect data to come up with an answer, or facilitate the basic problem solving mindset.
Guns in D20. Pulling a trigger should be easy enough to allow multiple shots, Ill be checking on some rules regarding that. Suffice to say, I'm open to running some other d20 settings and games to ease players into other systems.
"encounters that consume X% of the Party's resources" I can imagine how to capture this data, but I think there is a better way to visualize an encounter or scenario. I'll just come up with a flow chart and how as a dedicated post.
My brother tells me he has Savage Worlds, so I got that covered. He also has Warhammer Fantasy, Rogue Trader, and 40k books. I could try those out, but I'm tempted to either use GURPS or D20 to ease the learning curve. I hope this new year, I can run some games.