I’ve had a pair of Mag Ti Nuke Proof pedals for about 12 months. The axles are fine and are now sat in a replacement pair of cages (I bought a set of alloy bodies with chromoly axles because you can’t just buy the cages!)
The cages are where the weight is really saved. To illustrate, after I’d swapped the Ti axles out of the Magnesium bodies and put them into alloy bodies, that pedal still weighed more than the magnesium body with the chromoly axle.
But the probem is the magnesium body is really soft, as has been noted above. The reason I had to replace the cages is because a lot of the pins had been ripped out and when they rip out of magnesium, they strip the threads as well so you can’t just replace the pins.
Otherwise they are excellent pedals and the Ti axles have survived me (105kg) doing some reasonable sized drops.