Why not set up a battery back up to help ensure 100% power continuity - if the multiswitch is already designed to be powered by a separate 12v PSU a 12v car battery would be easy and keep it going longer than you need - add a solar panel charger and you might not need any mains.
What LNB is on there now .. a C120 + feed horn or lnbf?
How good are the signals now for the 8? Do they lose 2D at times?
If you change that LNB to anything else, just that can easily cause signal loss (or gain) depending if the LNB on there now is working very well so you could lose signal with a quattro before it gets to the multiswitch.. and a multiswitch can cost some signal. Systems here usually spec an 80 dish instead of a
Sky dish partly to compensate for loses. Check if there is a loss quoted on a particular multi.
You can do a search top right for other threads for 28e for that area.