I do not think we can make any formal support statements on combinations which were not tested. (Hence the exclusion of non-typical client OS from the client section of the support guide.)
With that said... I believe in most scenarios the client OS is not going matter in terms of most features. The areas where you will want to be concerned with, is if you have any client side desktop integration features (e.g. Word Merge, Edit in Excel, etc). That is where the client OS is going to most certainly matter.