The mics on the Edirol R-09 have been confirmed by some pro audio people (with good ears used to expensive studio mics) as being pretty good for what they are, and I've also read that Edirol put quite a lot of engineering effort into their design. I believe a similar effort was made for the Zoom H2 and H4. Frequency response figures don't tell you much - the mics are a good as you'll get given the constraints of being built in to the recorder. Very few mic manufacturers give you useful or truthful specs anyway - maybe Neumann and Schoeps... If you want better you need to spend at least the price of the recorder again and then your pocket gadget becomes a suitcase full of mics, cables and possibly a preamplifier and it's all not as portable as it was.

Anahata