Edge corrosion wt...

Welcome to the PNW, where rust, moss, mold and dryrot echo the long gone old-growth rainforest that thrived for thousands of years on the very spot where my La-Z-Boy now sits, as well as where you store your board. The rusty edges are just as they should be in this environment. Embrace this oxidized connection to place and it will make you an enlightened rider (plus the snow is so sloppy here, you really don't need edges).

.... Some bases are more susceptible to shrinking than others...

Have noticed the same.   Anything to do with extruded vs. sintered?  Not sure what sintered is actually..   had to grind the heck out of my TMX's last fall to get rid of the cup, but I'm thinking they are sintered.  Thinkng also, my pattern base boards are extruded bases, and I know they morph easily.

btw JibberD, funny stuff..

I go over the edges with a gummy stone. Try to keep away from the bases -- you don't want to embed the stuff in the base. Real rough spots (curled edge) or pits can be tackled with a normal stone. I try not to file the bottom of the edge unless I really have to -- you don't want the bases to be higher than the edge. Most of my filing is on the side of the edge -- 1 degree bevel.