It's really an individual matter. ShyShy claims to feel exactly as capable as before the surgery, just taller. He did say that his biomechanics changed, but he simply adapted to it. I think that femur lengthening might allow for better recovery than tibia lengthening. Femurs have more muscle and blood flow after all.
I think its the opposite actually, i think tibia lengthening allows for better recovery than femur lengthening. My argument is that while the muscle is stretched regardless which segment you chose, the muscles in the calfs and thighs are used for very different things.
The calf muscles are seemingly used mainly to move toes and feet as well as working as a damper for your legs whenever your feet lands on the ground. In other words, these muscles are not primarily used for movement of the whole body. The thigh/upper leg muscles however, are the primary muscles which you use to move your legs around, its from them you generate force/acceleration to move your body forward.
This means that if you weaken your thigh muscles through LL it will likely have a bigger effect on your ability to run/walk/move compared to if your calf muscles where weakened through LL.
Also with femur lengthening there is the added issue with the mechanical/anatomical axis being changed.
Having more muscle and thus more blood flow only means the healing will go faster, so the difference in blood and muscle should not have an effect on the end result in terms of recovery.
Thats what i think at least.