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10" f/4 vs f/5 - coma is the only main difference. It is much more aggressive in an f/4 instrument than f/5.
Best way to relay this is with my own experience with my Newts from f/4 to f/5.
For EEA using a small chip, say 1/3" size, at f/4 there is no coma to be seen. As the chip gets larger, coma will begin to appear, but really for EEA it may or may not be a concern for you. With my 1/3" chip camera, I don't use a coma corrector, and certainly at f/5 even less need to so.
Visual, the only time I use a coma corrector is with my f/4 Newt when using 30mm and 24mm 82° eyepieces. Not vital, but it does clean up the image especially with the 30mm. But remember, I am using eyepieces specifically designed for Newts, in my case these are Explore Scientific EPs, so there is no astigmatism present, only coma. TV eyepieces are also brilliant in Newts. If you use EPs not designed for Newts, any aberrations seen with them in an f/5 Newt will be much more prominent at f/4. Careful eyepiece selection becomes more important with very fast focal ratio Newts.
I hope this helps you.
Alex.
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