I have a shredder and run the poudre, ark, and a lot of other stuff. Chris drop me a line when the water starts to rise and we can hit it.
Stingingrivers - I got my shredder last winter, only R1ed it twice, humbling both times. I am confident guiding my 14' raft down class V, but class IV feels a bit sketch R1 and even R2 in the shredder. In contrast I felt solid R2ing in a Puma and Spyder doing class V and even some V+ (Upper Taos Box, Big South Fork Cache la Poudre). I'm looking for advice. Mainly I find it a lot harder to maintain control of my angles in the shredder, especially with novices paddling in the boat with me.