I'm looking for a beard/stubble trimmer myself. I've never used one but my brother has, and he says that the hairs lie flat and that the comb/guard doesn't raise them and the clutting head misses them. This is a problem that I foresaw before he even told me that. I can imagine that it would be difficult for these trimmers to catch hairs which aren't beyond a certain, fairly long, length.
My brother's trimmer was a pretty cheap one, but looking at the range available they all seem to have the same basic design.
Can anyone give me any advice?