I have installed a Wave in both of my FGRV's. If you are handy, it is not very difficult. The biggest challenge is running the new gas lines. The only tools you need that you might not already have are a "flaring tool" for copper pipe, and a pipe cutter.
I just installed a Wave in my 16' yesterday, and it took about an hour - this includes running the new lines and hanging the heater on the lower portion of the closet. Make sure to use teflon tape on the threads, and check the connections with soapy water for leaks
when installing. Also, it is a good idea to use a flexible hose for the final connection to the heater.
Many RV places refuse to install Catalytic heaters or work on gas lines, and if they do, they charge an arm and a leg. It is worthwhile to learn to do it yourself..