tremere110: if you don't have the DLC you are at a major advantage against the AI because they can access DLC benefits but you can't.
There are
very few cases where the AI can access DLC content that you don't own. I think it's
just civics, and most of the best civics from a strict power standpoint are in the base game anyways (Meritocracy for +10% specialist pop output isn't very flashy or interesting but is
incredibly strong) so you're not at any disadvantage. However, there are actually many cases where the opposite is true; there's a whole bunch of DLC content that the AI was never programmed to use so even if you have that DLC purchased the AI will never use it. There's also a lot of DLC content it's not very good at using, to the point at which it basically gets no benefit from it.
Xeno-compatibility is the most notorious, to the extent that Paradox actually added an option to disable this perk from your game entirely in this update; that's how bad the AI is with xeno-compabitility. It's actually a really solid perk, provided you use gene-modding to fix the random genetic junk that your hybrid species inherit, and consolidate redundant hybrid types into a single subspecies. If you just leave them to randomly propagate, as the AI does, then after a century or two you'll end up with literally hundreds of subspecies with nonsensical genetic combinations. And if you sign migration treaties, they will spread their nonsense across the entire galaxy because none of the other AI's know what to do with them either! In the late-game this can get so bad that it makes the species management UI unmanageable and actually cause performance issues due to just how many subspecies the game is tracking because the AI never consolidated any of them.
Krogan32: and more strategic decisions rather than currently of, "Put overwhelming defenses at the chokepoints."
I will say that 2.6 made choke points much less effective as a strategy. If you sit back in a war and let the AI just muster its forces for a few years, it will literally send
everything it has in one big push against your choke point (as it should). With the caveat that I do play on the highest difficulty setting, my experience is that the AI can very easily break any realistic choke point and you're much better going on a counter-offensive in a war rather than huddling behind choke points.
BitMaster_1980: Do you have an example of where that put base game players at a *significant* disadvantage?
There isn't. As I mentioned above this isn't a real problem, and if anything the issue is the opposite where the AI doesn't know how to use certain DLC features so if you do own those DLC's you're at a massive advantage over it and the game will be much too easy.