I play with both Aiming Angles, Red Fog, and that one with criticals-when-flanked. I think they all help me more than hurt me, too.
People kept insisting the same thing about Damage Roulette and Not Created Equal/now not taking Strict Screening until the math and research was done that definitively proved that they're fairly detrimental to your performance over the course of a campaign. Red Fog in particular doesn't really become noticeable until fairly late in a campaign, when you're running through the real slogging missions and are forced to continually take on waves of fresh enemies with injured soldiers. It's not necessarily unrealistic, but I'd posit that if you're looking for realism X-Com might not be the right choice.
That said, Absolutely Critical is a good example of a SW option that is both broadly beneficial for good players
and fairly balanced. On the face of things it affects both you and the AI equally, but if you're careful you can turn it into a very strong tool on the Battlescape. Naturally, it means you lose more people if you play sloppily, but if you play well then it means you don't have those situations where you attempt a flank and then roll non-crit damage and your dude gets killed the next turn by a crit through full cover. It also makes it easier to train up PFCs.
By the same token, though, AC serves to magnify the bullshit of AA. But to each their own, I suppose. I'd rather play on Impossible without the shitty SW options than on Normal with them, because the former leans more towards punishing me for my mistakes in game and less towards punishing me for my mistakes when selecting SW options.