OK, after some more experiments, here are my thoughts on the differences between the latest version of FF and Chrome - make of them what you will.

(1) Without doing a formal bench-mark, the speeds of both are similar.

(2) The recommended FF adblocker (uBlock Origin) works well.

(3) FF coped well with my two "high-security" sites - Internet banking and doing my tax return on-line.

(4) I prefer the Chrome layout of bookmarks (top of the screen) to the FF versions (left or right of the screen). Not a big issue.

(5) I dislike the FF response when I open a new tab, which I only do to start a new search. In Chrome that takes me to an uncluttered screen where I can type in the keywords. In FF it is very cluttered - a whole bunch of irrelevant stuff.