Thanks for that, Arsheesh. I'll keep that in mind to experiment with. If you're interested in playing with it, here are the settings I used for the Felimage Noise filter -

Seed - I just kept clicking New Seed until I found a pattern I liked.
Width & Height set to 15 pixels
Sparse Turbulence algorithm
Ordinary fBm octave blending method
Octaves - 5.0
Lacunarity - 2.0
Hurst Exponent - 0.50

I found that if you load the Channel for your Forest Outline while setting options you can actually use the Preview function to get an idea of what the render will look like specifically inside your selected area. Clicking the New Seed button lets you preview new renders of your forest texture before you actually render it. Just make sure you Select > None before you Ok your settings on the filter.

I used all the above in place of step 2 of the tutorial (Filter >Render > Clouds >Solid Noise)