Difference in considering RAM between iPad4/iPadmini?

I'm going to go out in a few days and pick up either an iPad 4 or an iPad mini, given that there are strong rumors that Apple is updating the iPad line in the fall (even if it's announced in April, I'll be eligible for a return). But while I've already considered things like portability and weight, I'm even more concerned about the RAM difference between the two.

That said, I'm currently leaning towards the iPad mini, due to its portability, but the 512 RAM it has on it worries me greatly, and my gut tells me that the current mini (because of the RAM) will be slow like crazy after at least one more iOS update (I had a 4, and it's terrible on iOS6, no matter how many resets I do).

So, I turn to you guys - simply future-proof wise, should I go for the iPad 4 instead? I don't care about things like retina/non-retina, and care more about portability and reading on the subway - but I care even more about experiencing lag 4 months down the road because of a lacking RAM.