The M2 plays cleanly to ~100dBC @1m without a sub. The M5 does the same to ~103dBC.

With a sub crossed at 80Hz, the M2 can be pushed to 103dBC cleanly. The M5 can be pushed to 107dBC.

I've used both, in bookshelf form on stands, in my 4400 cu ft room as fronts at a 14 foot MLP. Both acoustically disappear very well with the advantage going to the M2 in that department.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated