Not unusual. I'm assuming you use line-in.
My advice is not to set the M10 level at more than 5 or 6. The control is non-linear. Between 6 - 10 doesn't add much.
I normally set my CA9100, used with Church CAFS, to around 4 o'clock (the knob marker at the red light) for acoustic shows. Yes, the levels are low, but boosting them in software is fine. Better low than high.
Battery drain difference will be negligible regardless of setting. I change mine every 3 shows just to be on the safe side. I remove it between shows. The only issue here is the battery connector Church uses. First thing I did was change it. It comes with a 6-lug female connector. A 4-lug one can be tightened up, as removing the battery makes the connection loose. Just remove the connector from an old battery and solder it in to the CA9100. A little thing, but a good battery connection is vital.