The settings in this situation would all be set to the middle. Just trying to get my head around what difference I should expect to feel on the bike.Unless you are towards the rebound adjustment range in the current shock, you should still be fine with rebound setting.
Assuming this is a fox float (or similar) the additional compression damping may be welcome if you are on the heavier end of the spectrum. But if a light rider who prefers ‘comfort’ settings for your suspension then you may be disappointed.
So going from L to M in rebound tune shifts the range of possible settings?
L = 1 to 6
M = 3 to 8
H = 5 to 10