I would consider the AKG D5 or D5S, it is a great Mic that is Supercardiod and is very hard to get feedback even at close distances, my friend Michael Carollo used EV ND Series and Sennheiser E series, and got feedback, since he switch to AKG D5S, he so far is been Feedback Free, and sounds amazing too.

The AKG D5 has a Step down model, the P5 and P5 S, (The S is means that have a Switch to turn off the Mic on both Models D5S and P5S).
And the best part is the prices without compromising High Quality audio:
singer

http://www.amazon.com/AKG-D5S-Profession...eywords=akg+d5s

http://www.amazon.com/AKG-Pro-Audio-Micr...eywords=akg+p5s

I own both models and other than cosmetics, you can not tell them apart for the Audio Quality.
I use them on my Demos/Clinics for the PSR S950/S750 also in my performances with the Tyros5, and also use them to record some Audio Multipads, both are amazing.
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mdorantes