Common sense would lean towards a 22mm axle over a 19mm for stifness and strength, and the opposite for bearing durability.
The problem with LH Wombolt cranks was the cluster, not the arms, easily fixed. No comment on the newer Twombolts.
Although the luftalarms are heavy, they're solid. I ran a polished set with 25T sprocket and bash, tried to break them with repeated pedal grinds, sprocket abubacas and sprocket slides with no success.
And I'll be bolting them back on again in the near future.
Mikey.