So, once you have pinpointed the psion (which is not as easy as you said, because of the +20 modifier), you can use ray spells, which have a great chance to miss, or you could use area spells (without pinpointing probably, a rough estimate would be good enough here).
Now, don't you feel, that this is quite a bit of a disadvantage?
Yes, you won't be turned to stone, but with that disadvantage, you will surely lose the combat anyways, unless you have a number of area spells ready, which could save you then (of course, if the psion is close to you, you might hit yourself with them, too

).
Anyways, this is just one example, I was only going to point out, that your "closing eyes tactic" isn't really that great in the end. I'm pretty sure you see some problems there, too. It might work (not saying, that it never will), but it still leaves you in a very bad position.