....and regarding my point 4 above (from earlier):
The company which did mine didn't let me down or disappoint me and the system has been functioning well, without any problems (and as a former scientist, I have been monitoring it quite closely).
So I would be happy to recommend the company to family or friends (but they aren't getting free advertising on here so I am not naming them!).
Because I have been happy with my system over the last several months, it gave a relative the confidence to deal with the same company.
Their installation was completed yesterday - and, again, it was a nice tidy job; excellent.
So now both myself and a relative would recommend the company. In fact, the company have my permission to give my email address to any prospective customer who would like to ask me a question.
Word of mouth from satisfied customers counts for a great deal when it comes to inspiring confidence. I expect that my word of mouth and that of my relatve will probably generate at least another couple of sales for the company.