I've used extenders for several years on Campagnolo Centaur (aluminum) and Chorus (carbon) cranks without issue. Can't the length; it's either 25mm or 30mm. Both of my feet point outwards; one more than the other, due to arthritic deformation. I didn't use them when I first started with clipless pedals. The twist that you put on your knees and hips was not good. Using the extenders allowed my feet to be in their neutral position with no twist and not hitting the chain stays.

Regarding the titanium extenders, I assume that they are designed appropriately. Titanium is aboiut half the stiffness of steel, so you would need to account for that in the design. It is an interesting solution, however. I originally used the extenders on Crank Brothers Quattro road pedals. They are now discontinued, but basically they were Eggbeaters with a surrounding platform structure. I had someone I know who runs a machine shop drill out the stainless steel extenders that I had. A couple of vendors that I talked to did not want to sell their extenders drilled out for fear of broken parts and law suits. This had limited usefulness as you could get to the hex in the pedal axle, but you were forced to turn on the short end of the Allen key and that limited how much torque you could apply. T-handles would have helped a bit, but it still wasn't a complete solution.