To be honest I don't consider either my 25 or Zaan (old pivot with LBS) to be very ergonomic, the fit/finish is what sells me on them but if I pick them up and handle them with my eyes closed and really concentrate on the feel and especially over extended use (with my eyes open!) if I'm honest with myself, I have a few knives that for me are much more comfortable (560, VCEP, Manix 2, PM2, Socom). Less "hot" spots and especially more comfortable in different grips.
On the 25 I don't like the small first bump created by the first and second radius across from the end of the lock bar, my index finger always seems to search for and never find a comfortable position, especially if I choke up on it to use the thumb ramp. It also seems to be made worse with the large handle/lockbar gap on the other side due to how far the lock bar drops inside the handle line when open.
On the Zaan the extra fin on the lockbar makes for a similar difficulty for finding a comfortable index finger position and I also feel the clip bite into my hand a lot more in extended use than I do on the 25.
I'm not getting rid of them anytime soon, but they certainly don't melt into my hand like my 560/VCEP do.