I vote for variety, as long as there is game balance and rationale for it. Having 6 versions of the M-16 rifle is not what I'm looking for but having real, practical variation in weapons makes sense. I know this is supposed to be the 1970's so there is a limit to what can be done, but for instance I could see something like the M-79 grenade launcher eventually evolving (with alien tech inspiration) into something like today's modern laser-assisted XM-25 GL. Shotguns could evolve into full auto versions, pistols could get laser sights, etc. Sniper rifles can evolve to bigger bore (e.g. .50 caliber) and/or more precise, longer-range versions. Also it is not clear yet what effect, if any, weapon reliability has upon the game. New/experimental weapons should have more breakdowns, while others like the AK series should be quite reliable but perhaps less accurate compared to, say, the M-16.