I broke down and bought a Tormek several years ago and like it a lot, but I still have problems with wide plane blades. The middle of the hollow grind tends to get concave or "lower" than the sides of the blade, so when I go to a stone for honing, a very noticeable portion of the hollow grind gets flattened on both ends of the blade before the middle of the blade gets honed. Once and a while I get it deads nuts on and my time on the stones is really quick, but I just put a hollow grind on my #7 blade last night and it ended up concave again. Does anyone have a method they use to minimize this.
PS: It's not the flatness of the water stones, but I do apply more pressure to the edges of the blade when on a water-stone. I don't think this pressure is the issue.