As Freeier says, the difference between RTL and ROA is tiny. You get to vote in meaningless rigged elections, and er, that's about it now that the double property stamp duty was abolished.
Oh, except I guess you need to go through ROA if you wish to naturalise as a HK/Chinese citizen, but since you are sending your child to another country to avoid indoctrination in the schools here I guess that isn't your goal.