I like the RC-3/4 handles. They are identical in every way except for the thickness. I know, I've laid them on top of one anther for a shot in another post.
What I can say is this. I have a lot of knives that have thicker scales and when you hold them its like sitting in one of those big soft fluffy couches. It seems great, but when you sit your butt on that fluffy couch for 3 hr, pretty soon you back is all out of wack. Now, if you sit in the stiff chair in the corner, it don't feel like heaven when you sit down but 3 h later your back isn't screaming bloody hell.
The RC-4 handle is like that. When you grab hold of it, it doesn't feel like a soft comfy couch. It feels like the stiff chair in the corner. After using the RC-4 for some hard work - that is when the comfort and ergonomics ring true. Since it would seem a lot of people make decisions on knife ergonomics by holding it for 30 s then this is probably why it gets a bad rap. Thats just my opinion, however, I have a few comfy couch handles that follow suit with the aching hand after using them. I've grown really weary of handles that sport aggressive contours - they feel good at first and bad later.