Just got out on the 170 Fish for the first time today. Background; Newbie, as I've been riding the 170 'classic' since I started foiling this past September. I can jibe on both sides, regular or goofy. I cannot switch my feet. Flat waveless water, 9m foil in 8-15mph.
The fish is a very different wing than the 170. The wingtips are curved down more, the foil is much thicker (and heavier), and as others have noted the fuselage is flat towards the tail. It comes up very quick out of the water, but once moving is stable (though not as stable as the 170). I felt I needed to have my back foot further back, but that might have been my inexperience with it. It turns on a dime compared to the 170. Carving turns felt a bit more confident than with the 170, and that was in the first session. At moderate speed, 'pumping' did not feel entirely different than the 170. At very slow speeds it feels nose heavy (could be placement on the board); once the wing is stalled, it falls more dramatically than the 170.
Again, one time on the wing, from a relative newbie. I bought it with the option that I might sell it if it was not good for kiting, but I don't think that will happen. It will add some variety and a challenge, which is what I wanted.
Lift 170 'classic'
Lift 170 Fish
LIft 170 'classic'
Lift 170 Fish
Hope that helps, cheers