Baby backs cook faster, that is for certain.
Yes, you can get spares and BB to fall off the bone stage with no foiling, just a matter of time and heat. Foiling makes it easier and more predictable to get them done to a certain level and color.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."