Depending on the species of wood and the bore diameter, the handles are surprisingly light, adding only a few tenths of an ounce to the overall weight of the rod compared with a cork handle. I don't think that will affect your arms even while fishing all day.

All my wooden handles and inserts are finished with 3 coats of polyurethane to seal the grain and prevent swelling. I have fished them in the rain, and if anything they become a little tacky. Fish slime has never been a problem either when handling the rods. Landing nets have wooden handles and get wet all of the time and I have never had one slip out of my hands while landing a fish. Cork has a tendency to swell and crack when exposed to the elements, wood will maintain its luster and never crack or pit.

I believe wooden handles give better feedback because they resonate more than cork. Think of hitting a ball with a baseball bat, you know when you hit the sweet spot and when you hit it on the end of the bat.

Yes, I have retrofitted some of my favorite fly rods whose cork handle had been beat up, pitted and cracked over time. In most cases the reel seat hardware on the existing rod can be salvaged (depending on the epoxy seal) and a new custom turned insert can be installed. The fly rod needs to be shipped to me for retrofits.

Of course, there are many rodbuilders who don't have access to a lathe who would like to add wooden handles/inserts to their rods. I just need to know a few dimensions from the butt piece of the rod, type of wood needed and style of grip for the handle. I will also need to know the type of reel seat hardware being used, in some instances, I might have to have the hardware sent to me to ensure a proper fit.