All I have to say is different strokes for different folks. The posilock set up offers more than just a secure way to engage the front axle, it offers a secure way to disengage it too! Whether you're running a lunchbox locker or have your front spiders welded that option can give you better steering capability under high stress situations or just 2wd low range with an open differential up front. Off roading is as much about tactics as it is horsepower. The solid front shaft has it's place too and as far as I know it's the only way to get chromoly steel in the Dana 30. On the cheaper side it is yet another way to just adios the cad system that relies on vacuum lines that crack and sometimes pull out. The xj shafts are easily found in wrecking yards and on CL being parted out all the time. But the easiest way to solve which option is best in the front axle is to get another e clip and lock the fork over on the cad itself and walk away. Costs $5 if you don't have rtv sitting around.
Now you two, quit your bickering over semantics!
Luck Favours The Prepared