If you have directly connected your controller to the AD via RADIUS (Using NPS, IAS or another RADIUS server) I cannot think what changes in your AD domain level would cause issues. I can't think of issues if you used LDAP to connect either as both methods are pretty basic and don't use domain level specific things.
I always used the same settings, never looked at domain level. Also raised domain level in my lab two times and that did not have any results.
I can't say it will not cause issues in you specific situation, however I never bothered or saw issues before.