I've tried the pro 3 and never got the knack for it, went back to the kme.
I've tried the edge pro, had good results, not very mobile as I had the one that suction cupped to the counter.
walked away from knives for a couple years.
Came back to the kme, got tired of flipping the knife over. Went to the we66 and it's an improvement over the pro 3. I don't do the micro adjustments on each side, I'd rather have them be the same angle on each side, so I tried the pro 4.
So for the pro 4, I went with no storage and no adjust. Very easy to pick it up and move it when needed. I really like the locking mechanism they have added and it does half degrees which I could give or take but it does add to it. 12 to 28 degrees, without the micro adjust, I can't do over 28 degree angle. No loss in my opinion. With the veteran discount, that took it down a bit and I'm pretty happy with it. Doesn't look like an erector set. I store it on a desk when not in use, bring it in the kitchen when in use. It's up and down that quick and easy to use.
Also forgot to mention that the pro 4 changed the rod installation. we66 has the ball joint and the pro 4 has the screw in rods. we66 gives you the circular grommets to stop metal from getting in the joints, you don't need that with the pro 4. the joint system on the pro 4 is stiffer, not in a bad way. Your stones don't flop around like the do with the we66. I really like the pro 4 joint system much better.