Hmm, the man page says these options are related to search highlighting. With + you are disabling them but since they are already disabled by default, I don't know what this does.
By the way, I tried adding only -M and I get both line numbers and percentage displayed in the footer.
From: Jaskaran Veer Singh <email@example.com>
In pager, show current displayed line numbers, and the length of message
(in percentage) currently visible to the user. Should help in reading