Desert Olive & Colorado Blue Spruce

The workshop list has been posted for next year's convention in Denver. Looking for something I can afford & will be able to grow, I am interested first of all in Desert Olive, Forestiera neomexicana. There are a few nondescript pictures on the Internet, as it seems to be a new species. It comes highly recommended, but I would like to hear from someone who's tried it. Is it really good & not too difficult? Any problems with winter storage (apparently it is hardy to Zone 4)?
The other puzzle is Colorado blue spruce. It is featured in several workshops & seems to be highly touted. However, in the past I have heard that it is not a particularly good bonsai subject and only suitable for beginners to practice on. What are the facts today? Is it only good as a yamadori?
Iris