One head holds 30kg the other 40kg; one costs about $500+ the other $600$. Unless you've got some seriously heavy gear, the Q3 should meet your needs. However, if you've got a camera that's bigger than the entry level DSLRs, they would look better on a M10, eventhough the Q3 would be enough to hold them.
M10 looks better on a 190 Pro but if you are using something like a Gitzo 55T or similar than the Q3 fits like a glove. The M10 is slightly bigger and heavier but both should be able to hold what you described.