Electric vs gas spa heater
Analise the two heating systems and then choose one that best suits your needs.
If you choose an electric system, the biggest problem that you will need to face is the problem of electrocution. One way to avoid such problems is to move the electric parts away from the space, but some spas may have the electrical feeding directly into the cabinet.
You will need some special tubing for the gas heating system. The tubing will need to be installed by a professional that will need to have a special license. The installation process may require some flaring tools, special tools made to cut copper tubing.
Ease and convenience
If you want ease and convenience, you should choose the electric heater. The heating will take a little longer, but the installation is much less complicated and also there are less things that can cause problems.