Well the -5 lvls gaps (while not explicitly mentioned anywhere) is still not contradicting anything in the description. As per my post above - on characters with class(es) at LVL50 (and most certainly almost always iLVL55+) it will allow you to have reainers up to level 50 - so it might be intentional while "undocumented" behaviour rather than bug. We definitelly need dev's clarificatoin on this.