Should I or Should I not?

[extrememc]

Hey looking to build a hexcopter F800 with Naza V2. My LHS has never build one but says they can build it. They do carry quad etc, but no DJI products. Now I can either have the dealer that I am purchasing the hex from build it or LHS. My thought on having the LHS do it is I can always go in a get help with it when I need it and I can watch the progress of the build. Should I or Should I not let the LHS build it? My next question is if I have them build it should I get something in writing that if anything is gets damage motor, FC, etc they are liable for the cost?

Thanks in advance for the advice!