I agree with Bill on this. My own choice would be guided entirely by which sounded best to me at the time.

I have noticed, over the past ten or fifteen years, that this alternative construction has been carried over (usually, but not always in a jocular vein) to other words. So, one is neither "frighted" nor "frightened", but "frit". Which, I suppose, makes the agent of afright a "fritter"