Preference and rope configuration. The fimblesaver has a large and medium thimble combo, whereas the climb has medium and small. If you have sewn splice, the saver is for you, as the thimble on the climb is too small to pass the splice. A hand splice will pass through the small thimble with pressure, depending on the rope. I doubt vortex will fit. When retrieving, the splice will catch before the ball most of the time. I mostly leave my ropes unspliced, so the small thimble works great.
My latest friction saver concoction is running a 10mm rope, preferably htp or similar, through the large thimble, and tying off the ends in the same way the new treemotion terminates it’s double bridge. Then add the small or medium thimble on a prusik. It’s stiff like the fimblesaver, and cheaper for me, since I had the thimbles on hand.
