Moy Grande Advice Needed

I was just wondering if any of y'all had started any Moy Grandes from seed. We've had ours two years and have some friends that wanted some. I've tried taking cuttings this year with very little luck, (most just died and still no roots on the ones that are green after 5 weeks).
A friend of ours in TX assured us that you can just save the seed and get the same size. I don't want to argue with them but I know that they're a hybrid,(see below) and I don't believe that they'll come back true with such large blooms.
Any input would be appreciated.

"Hibiscus moscheutos 'Southern Belle', which usually has 8 inch diameter blooms, was cross-bred with Hibiscus grandiflorus, which usually has 10 inch blooms, to create Moy Grande which has 12 inch blooms. Most gardeners have been settling for the comparatively small 8-10 inch blooms."