SAS or St. Joseph International for my daughter?

[Kendo]

We are an American family about to move in the summer to Singapore from the East Coast. Our 11-year-old daughter has been accepted into both the Singapore American School and St Joseph International for the coming year. We really don't know what to do about it, and wonder which might be more rigourous for her? She's a smart girl, with a great work ethic but and intellectually appropriate for her age; she does love the Arts and Dance. We do know that she'll have local Maths and more Mandarin instruction at SJI and also will mix more with local kids when she gets to 7th Grade, but the facilities are certainly better at SAS (we've toured both schools). We also know that SJI is a new school with a limited track record but don't know if that's a bad thing, so looking for advice from you wise folk. Thanks.