The Griffiths is listed as new - at that price the tree has been cheaped on as well as the steel pommel bridge. I've dismanted both high and low end saddles and it's what you can't see that makes all the difference.
I know Coaldale, spent a few summers on a farm just east and north of there when I lived in Lethbridge.
The reason why I'm looking at 17" and 18" saddles is because I have longer legs and a big butt and I'm not sure if a 17 will be enough.
Rider, how tall are you? If you are decently tall and with longer legs look into 17.5 - 18". I'm tall with long legs and simply don't fit into 17". And if you plan on jumping look into A/P with more forward flaps (although Zaldi seems to have really forward ones).
I'm about 5'8" and have quite a lot of leg, that's why I think a bigger seat would be more comfortable for me. I can share a photo of me sitting in a 16" saddle.