Natural gas piping is done at such low pressures in residential environments that it's basically a joke. I think it's about 0.5psi (or 14" of water column) which in the grand scheme of pressures is very low. People can generate greater pressures with their lungs.

http://hvac-talk.com/vbb/showthread.php?1587361-What-is-typi...

http://www.personal.psu.edu/ref7/apparatus/2003%20competitio...

EDIT: I'm not saying that one should do their own natural gas piping as in many places it's technically illegal unless you're a licensed plumber. But it's certainly not rocket science. The only reason it's "harder" than plumbing compressed air is that if compressed air leaks a tad, it's no big deal. You have to get rather tight on gas piping because of the consequences of a leak, not because it's so difficult to get it tight.

I think that was the GP's objection to DIY. Not the actual installation process, but long term leakage issues if you do it incorrectly.

In Most of Canada and a lot of northern states, if you have no insulation then you soon won't have indoor plumbing, but you'll have a nice ice skating rink in your house.

In all fairness - People have been building houses in similar climates for 5000 years, and while they didn't have indoor plumbing, they surely built their houses to some standard of insulation.

I was reaffirming the reasoning behind rtpg and Pxtl's prioritizing insulation over indoor plumbing and further explaining why it is a necessary pre-condition to indoor plumbing.