October SK reviews the WHISTLER as a transistional kayak.
Is the hull design appropriate for river touring ?

One might have to qualify whether on not a boat like the Whistler would be appropriate, depending on what you mean by "river" and what you mean by "touring." I'm pretty sure the shape of the hull wouldn't disqualify it from negotiating any water, short of where only white water boats would tread.

On the other hand, I once met a fellow who was touring the Columbia River in something like an Old Town Otter.

Most of those 'transitional' boats look like they would work fine on a river. I have several friends who do class 2-3 stuff in those sort of boats except without rudders of course. Just looking at the pictures, the Breeze looks like a better choice with no rudder and more rocker.