Go for it. E.g. there are no middle names among the French, and I have at least one ancestor with 5 given names, though I'm pretty sure I haven't seen six yet. They all go in the PFN field and if a preferred name out of them is known it goes in the PN field and the middle name field is checked as a negatory. The limitation is in the construction of the add profile and edit pages, so all we can do is work around that with common sense.