In my head there's little risk in replacing a fuse with a lower current rated model, the real question is are the fuses that you're taking out slo or fast blow types. I wouldn't want to replace a fast-blo with a slo-blo and there's no good way to tell what type of fuse it is from looking at the package as far as I can tell. Last question, were the fuses blown? If so, simply replacing them is probably a bad idea.