New tankless water heater

So, I plan on putting a tankless water heater in the attic of my home. I live in a two story home and the plumber who is quoting to install the gas lines says I need to increase the pressure at the meter to 1psi from the current 0.5psi or ill starve my stove and other utilities and I wont get gas upstairs. This would involve increasing1 psi at the meter and installing a regulator for upstairs and downstairs utilities to bring it back down to 0.5psi. He says we have to drop it back down to 0.5psi or I will end up with possible leaks because of the step-up in pressure. I have a hard time believing a 0.5 psi increase will result in any leaks. Does any of this sound legit. I'm going to get a second opinion, but I thought I would ask the HG board. BTW, he is quoting me $3k for 40ft of pipe, two regulators, some elbows, and a ball valve termination. Thanks