Felts are terrible in mud along rivers, esp. in steep spots. Studs might be nice if the rocks are really algae covered and super slick, but really just the felts are normally fine when wading.
I never wear studs because I'm in and out of boats a lot. I might put studs on if I knew I had to hike a lot of steep muddy banks. But as stated ^ then I'd probably just wear a cleated boot.