A few points.
Copper is allowed in certain areas of the country, and not others. It is related to the sufur content of the local gas supply. You will have to ask. The CSST tubing does require special tools, and skill. It was never intended to be a DIY product, but as mentioned, the $$$$ rules and it is now available. We simply do not recommend gas work as a DIY project. You don't have the skill to install, nor the tools to properly test a gas installation.
For CERTAIN, your city/state/county building code requires a permit for gas work, and in many areas they DO allow homeowners to pull a permit. At least then, the work will get some kind of inspection.
As far as WHICH material, I personally do not consider anything other than black pipe to be safe. There are very unique electrical bonding requirements involving CSST to prevent blowouts from lighting strikes.