From what I've seen on a projector the Optimos have less distortion, breathing and chromatic aberration than the DPs. However I was also comparing the Alura Lightweight zooms (priced similar to the DPs and with similar zoom ranges) and they performed even better than the Optimos. Definitely try to get a look at these lenses on a projector yourself if you get a chance.
I'm sure these people would be glad to help you purchase an Amira in Canada.
ARRI Canada Limited
(Sales & Service)
1200 Aerowood Drive, Unit 29
Mississauga, Ontario L4W 2S7, Canada
info@arri.com
Phone: +1 416 255 3335
Fax: +1 416 255 3399