So far I've climbed my "tree ropes" out in the maple with the hand Futura. On both worn BW3 and Mammut static 11mmm ropes the channel is just big enough for the ropes (the BW3 is more like 11.5mm). New 11mm, no problem, especially tight laid ropes like our beloved PMI Pit rope. The big ropes make it a bit more difficult to thumb the safety to place the ascender on/off the rope, especially one-handed.
I have yet to try out my Kong Futura foot assembly, but soaked it a couple times in the shower to hopefully shrink the webbing harness closer to future length. It looks very sturdy. Unlike the Pantin there is a metal (Stainless steel, I believe) L-shaped piece of metal that goes under the boot on the outside of the foot (opposite the ascender body). Like the Pantin, there is no safety latch to manipulate.
If you're having trouble with the webbing slipping on the Pantin, here is what I did. On the aluminum buckle I filed some v-shaped "valleys" on the piece closest to the foot. The webbing passes over this piece and these V's grip it. I've not had any problems with either of my Pantins slipping loose, and have been a Pantin user since 2001. One is modified with a small aluminum bar, shaped to fit the bottom of the cam, and attached with a lock nut and stainless bolt. As such, it functions as a safety lock to keep the Pantin from coming "kicked off" the rope.
Tomorrow I have a day out of clinic
so will try out the new toys in the maple tree using 8mm polyester and 10mm PMI Talon ropes.
Originally I thought the hand Futura would be a good upper ascender in my Mitchell system. Not so. I want to try it as the upper ascender in a Frog system. It is marked with glyphs suggesting "no 2-person loads" and load-rated to 100kg. My friends know I am pushing that envelope!
Dr Jay