My first acoustic guitar had a 43mm neck, and I think my stratocaster has 42mm or so. At some point I wanted to buy a better acoustic, but the one I had in mind had a 45mm neck and I was worried that this might actually be too wide for my small hands. But guess what, even with short fingers this neck, FOR ME, is actually more comfortable to play, than the guitar with the narrower neck. Having said that, for barre chords for example it makes absolutely no difference because the difference in width further up the neck wil eventually cancel out.

But this is all personal, and in the end, I really think this is a minor matter and definitely no make or break either way. In any case it's only a matter up at the first frets - down towards the bridge most western acoustic guitars have more or less the same width (correct me if I'm wrong). Try out different guitars if you must and practice!