If you use a lot of onscreen buttons on your 650, realize most of those will only be accessible via the phone app if you switch to the Companion, as it has no screen and a limited number of physical buttons. I personally would rather not use my phone for remote control. So unless I had a very simple system, I'd probably opt for the Elite or get another 6xx or 7xx series remote.
But the Companion does have the advantage of no line of sight requirement for the remote itself, phone app (if you like that sort of thing) and some RF, wifi and Bluetooth capabilities. Many people are perfectly happy with the Companion.