Josh from Sun Gain took me through their options and had no problem with me fiddling and adjusting the quoted system to get exactly what I wanted. He was able to give answers to most technical questions and the confidence in their products was a big factor in picking them.
Installation was punctual and quick, with the installers being pleasant and willing to take direction and confirm the system install with me before anything permanent was in place. The only minor issue was a fair number of tiles broken during the process with a number left sealed up rather than being fully replaced, which is acceptable but not ideal. I think for any solar installation on the tile it is a good idea to find a good number of spare tiles (10+) in advance so that the installers can easily replace anything broken.
Overall my experience has been excellent, I am happy with Sun Gain and would recommend them again.