The kanji version 付き合う contains only elementary characters with their usual readings. Is there a reason why it's still usually written in kana? Is there a difference in nuance when written in kanji?
EDIT As to why I think that it's typically written in kana, I just observed the following:
- My textbook (イラストでわかる日本語表現) writes it in kana.
- My dictionary (ウィズダム英和・和英辞典) writes it in kana in all example sentences.
- ことえり (Apple's OS X input method) suggests to use kana when I write it.
Of course that's not necessarily representative of contemporary use by native speakers, but it appears that there are some writers who strongly prefer kana.