Regaurding the ARB line, I just went and got some 250psi braided line for $0.49 a foot a couple of fittings and ran it through the frame rail on my ZJ to the rear axle.
It was about $12 and will stand up to a lot more abuse that the nylon lines.
If you run them well, the ARB nylon lines should not give you a problem, but I felt like I wanted to make something with a little more beef.
*EDIT*
This set up eliminates the push in fittings, I also have not expierenced any leaks, just use threadlocker on all the brass fittings, I used blue.
HTH