adprep 2012r2 in 2008r2 domain

I was reading through all the changes that 2012r2 makes when running ADprep, most seem to be fields related to auditing.

Are there any known issues to old devices XP, server 2000 after introducing a new 2012r2 DC to a 2008r2 environment?

Or any other known issues to any MS products, we have about every combination of MC products & versions running.