I have a William Joseph Exodus. I bought it a number of years ago because based on the specs, it should have worked as an ultralight overnight backpack for fishing/packing trips. Turns out they had a gargantuan typo in the sizing - the initial claim was 3000 cubic inches of storage, since corrected to 1100 cubic inches in later models and marketing literature. I ended up keeping it but find I don't use it much.
Instead, I combine a smaller chest pack with a regular old hiking backpack (GoLite Jam or Gregory Savant). I can store far more in the backpack and the combo works for day trips, and overnight trips. I can ditch the backpack when I reach my camping spot and keep fishing with just the chest pack, without having to lug the extra backpack along for the rest of the afternoon/evening. This setup also allows you to haul out 45 pound logging era artifacts, if you happen to stumble on them ;-)
Just my personal preference - I'd rather have a few pieces of versatile gear, that I can mix and match to get the combo I want for a lot of different scenarios. And my current setup cost less than half the Fishpond wildhorse. But depending on the exact scenario you have in mind and if you have the budget for it, one of the fishing packs you list could work just fine.
