I usually seem to kill Latios by paralyzing it and then hitting it with something SE. It'll take out one of my Pokemon (my T-Waver) but I've never gotten Latios swept (at least I don't remember getting Latios swept). It might have opened up a gap for something else (like taking down my Cressy so Mixape can sweep me), but that doesn't make a Pokemon uber.
If you have never been swept by Latios, then you have gotten lucky or have the prediction skills to switch into a counter. As to what you said earlier about 'opening a gap for your Mixape', this is particularly why Latios is so awesome. It has the defenses, movepool, and raw power to be a lot of things. I like to run a Physical Latios that takes out all the SpDef walls to let my Alakazam come in and rape. This
can make a pokemon Uber because 'if you can create a situation where it is easier for the rest of your team to sweep', it fits the Uber Support class.
You may also have a team that is, by happenstance, a Latios sweeper counter (your pokemon can switch in and kill Latios). That is the same with my team as well. But it is important to keep in mind that Latios isn't just made to sweep. My personal favorite Latios set is the Support Latios. I don't have the exact Nature or EVs, but its movepool is pretty awesome. Memento/Light Screen/T-Wave/(filler, probably D-Pulse). This Latios can Light Screen on any crazy Special Sweepers, then T-wave them or who ever they switch to, then Memento on them to lower their attacks harshly. Honestly, if you think Latios is only meant to sweep, then you aren't that great of a battler.
Another thing, Latios will probably destroy anything (if it was a sweeper after all) that has low/average SpDef when they T-wave. I think you either got lucky or T-waved with something high in SpDef. It's not a bad idea, really.
Getting back to the actual test, I have come to a very sketchy conclusion. I understand that there is still a week left of test, but I don't think anything is going to change. Latios is going OU guys. To start, it has way too many checks. Scizor, Metagross, Tyranitar, Blissey, etc. can switch in on ANY of it's sets and take it out. Second, Specstios, LO Latios, Physical Latios, Mixtios, and Support Memento are not particularly strong sets. While Latios packs passable attack and extreme special attack, Latios gets unlucky because of the high-centralization of its counters. Meaning, nearly every team has a set Latios counter, even if they don't know it. Lastly, Latios is frail. It gets unlucky again with its Dragon/Psychic combination. The stronger pokemon pack Dark, Dragon, Ice, Ghost, and Bug moves to OHKO/2HKO Latios with ease.
Anybody who is in the position that Latios is Uber is basing their opinions on two things. One, that Latios falls under the Uber Support Class. Meaning Latios's Support Memento set cripples sweepers and forces switches, causing the rest of the team to sweep easier. The second thing is that Latios usually takes down two or three pokemon and hurting others bfore going down. I'm especially referring to the LO Mixtios which hits just about every pokemon in the Standard Metagame very hard. If I'm wrong please tell me, but unless I haven't been paying attention in my Suspect battles I think I'm right.