I've only ever heard this form be used in the command "待ちな!" (Wait!), but just out of curiosity, I'd like to know what pitch accent rule(s) apply here. I thought I'd heard the above-mentioned phrase be pronounced as まちな{HLL}, but for some reason, that doesn't seem right to me, since this is a shortening of the なさい form, which is always pronounced with a pitch drop on さ. So wouldn't you say まちな{LHH}(さい{HL})? Following that logic, wouldn't you also say 食べな{LHH}?
What rule applies here? Is it the same for all verbs, whether they be accented or unaccented?