No you do not need any tyvek.
To correct your lingo, tyvek is a weather barrier NOT a vapor barrier. It is breatheable to let moisture out of the walls in case it gets in.
I am in the residential construction industry and we use the foil face and backed insulation all the time and tape the joints instead of tyvek. I'm not completely sold on the application on the house exterior. The stuff does not breathe as far as I know so isn't it like creating a double vapour barrier?
Anyways, that's my disclaimer. I think it's a great product. We put hardie over it all the time. We did have an issue in a windy area where the wind actually worked a couple of pieces of siding right off of the wall but I think that the boys had their nails set too deep. Hardie doesn't want you to countersink the heads at all and I think that the rigid insulation just gave enough play along the top edge to work the nails through the board. The nails didn't pull out, the board just worked right off of the nail heads. We've never had it happen on any other jobs. Hardie probably has a recommended fastener penetration into the studs. Talk to your local inspector for his two cents on the foil insulation. Good luck.