Honest, guys, this issue needs to be put to death. Whether "they" warp or not, and I don't doubt that wood tonearms are susceptible to warping, some wood tonearms are among the best I've ever heard, to include the Talea and the Reed. Vacuum tubes inevitably wear and change specs over time; do you wish to avoid vacuum tubes too, as a matter of principle? (Halcro, I know you prefer SS; that's not the point.) Cartridges wear out and change over time even while we are adoring them. Audio is an unstable hobby in general.
In the real world, modern tonearms are made by guys who do understand these properties of wood. Then the tonearms go to live in our air conditioned/heated living rooms; they don't sit outside in the rain. How much warpage over how much time is prohibitive? Does anyone really believe that a wood tonearm is warping at a rate that will ruin alignment and geometry within any period of time that makes this a real problem? Any evidence for that? Guys who don't like wood tonearms or who have some ax to grind regarding whatever metal tonearm he or she worships like to carp on this issue of "warpage". It's not a real world, real time issue. I don't really give a shit if my Reed has warped a tiny bit in the next 50 years. I have a wood Grace tonearm (which I just keep around for sentimental reasons) that looks by eye to be as straight and true as a piece of steel, after 30 or so years of living in a controlled humidity indoor environment. There are some theoretical advantages to a wooden arm wand in terms of dissipation of energy that can be said to be superior to metals, but I am not here to say that wood is superior to metal. I am just saying that wood is in the picture as an excellent material to use to build an arm wand, if the maker knows what he is doing. I have heard both carbon fiber and ceramic arm wands; they suck.