My son is learning E.nopi MATH now. I was worried about MATH in ENG might not be good for him in primary school. But I think we might be wrong. My niece is in ST Mary's now, her school changes to ENG MATH in P6 to get ready in Secondary school. I was thinking it might be good if we can let our kids to learn earlier and getting used to it. Personally, I don't prefer abacus as I heard that your kid needs to memorize the abacus in his mind. So every calculation is sticked with the abacus....
We suggest to think about our reason to take extra maths course first, if we aim to satisfy our child's maths interest, then what kind of language is not important. If our kid's maths ability is behind, need further study, then better to follow school's maths language and syllabus.