The problem of mods is that the AI doesn't understand them very well, and their implementation is going to be rough if and when Firaxis releases patch.
Besides, 2 or 5 units per tile doesn't address how ranged combat is broken, or that any stacking limitation is arbitrary.
What's really bad is the arguments that crop up in favor of 1UPT are just baffling and stupid, just like the arguments people make for multiplayer's implementation in Civ5 - literally one of the worst experiences imaginable, where players are obliged to camp on ticks, chew up clock, and can't even queue orders. When people defend that nonsense as an actual game, it's no wonder so many people give up on Civ5.
Moderator Action: It is so easy to dismiss the arguments of others by calling them names, like baffling and stupid. It is much more difficult to prove they are that by discussion. Please stop being so dismissive of others, as it borders on trolling, and discuss the topic instead, you might learn something.
Please read the forum rules: http://forums.civfanatics.com/showthread.php?t=422889
I'll be honest, the moment I heard Civ5 would use 1UPT I knew it was going to get reamed critically, even after several people explained in excruciating detail why 1UPT doesn't work, people who are better than me.
So yeah, that 1UPT doesn't work and creates numerous imbalances is not an opinion, it's a fact. That ranged combat is broken is also a fact, not an opinion. Basically everyone worth listening to has told me, regardless of their experience with Civilization or strategy games, the same thing, and this covers players old and young alike (so it's not even a "Firaxis is dumbing it down" argument - 1UPT isn't dumbed down, it's just dumb). The only arguments in favor of Civ5's implementation come from people who want to defend bad game design, and people with criticisms of Civ3-4's stacks of doom - some valid, some not.
I for one would much rather have Civ4-style SoDs than the implementation in Civ5. That way, the mechanics of the base game could be worked on in order to ship a product with far more replay value.
I suppose the best hope will be for someone to release an actually good TBS, despite limited production values. Easier said than done, but several iterations of 1UPT have shown why it's a bad idea.