I had a 2012 MES 40 which I returned because of problems I had with it, but while it was working, I had a great New Year's eve party where I was able to do 8 racks of ribs. That has my wheels spinning for this summer. If I get an extra rack for the Model 3, could I potentially do 10 racks at once, or would that be overkill for the heating element? Not a deal breaker for me, so please be candid 

The shelves are long so I seriously doubt that you will need to cut the racks unless you are smoking an elephant and 3 or 4 racks per shelf would be my guess. I don't use the very top rack holder because I don't want to be in so close to the top where the heavier smoke is exiting.