Really I think that is the main question you need to ask. Why? What do you hope to achieve?
IJ and Coastals are really going in seperate ways as far patterns. IJ's have those beautiful sunset colors in their bandings. To cross it with a Coastal would only muddy it.
As far as that JunglexCoastal, that was an exceptional individual and it is yet to be seen if that youngster keeps his nice color as an adult. Most of the time Coastal/Jungle crosses are dark, generically banded, and have a fair amount of black tipping. I know because the reptile stores in Colorado are filled with them.
Whatever apeals to you in that youngster can easily be bred in pure Coastals. You just have to pick your stock carefully. I personally love that golden color w/black markings myself. My striped male is just that and he's a Coastal. If you want something you can blaze an unmarked trail with. Coastals are the way to go. They have a lot of un-taped potential and they come in all diffrent colors and patterns. Most of the general stock will more than likely be crossed, but there are some real 'diamonds in the rough' out there. There aren't any real set characteristics for a Coastal yet. There is a lot of room for new types here. Just look at Jaguars! They are PURE coastals! Thats the kind of potential you can have. Just pick you stock with care. Pick the ones worth breedeing in your eyes and have a goal.
Hope this helps,
Darci