Back in the day here in the Intermountain section the mixed leagues were labeled 3.0, 3.5, 4.0, etc... and they worked exactly like the men's and women's leagues in that you were rated at the level or below for the league in which you played. Those leagues were great.
I agree that the 4.5M/3.5W and 4.0M/3.0W has taken some of the joy out of competitive mixed play.
My wife and I took up the sport precisely because it allowed us to play together, and we still love playing mixed together today. I think like any doubles, the key is finding a partner you enjoy playing with and whose playing style suits yours.
I have noticed one oddity in mixed though that I don't see in men's doubles, and that is that sometimes it seems the woman targets the opposing male player rather than playing to the weaker female player. My wife does this occasionally and I've noticed it from women across the net too. I think in my wife's case it has something to do with testing her skill against the male opponent, and when she beats him it's a bit of a thrill. I'm sure that's also likely the case for some other women, though I also think some female opponents just become so focused on me that they tend to hit to me rather than away from me.
This rarely happens in men's doubles. If one guy is stronger, he'll be avoided as much as possible.
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