Whether the troop is using the patrol method or not I don't think has so much to do with the troop size as it has to do with the Scoutmaster and the Troop Committee and how dedicated they are to letting the boys lead.
Bigger troops tend to have bigger programs, more money for equipment, etc. These are things that can be readily seen when you go camping with them.
Smaller troops may also have advantages, but those advantages are less tangible and no guarantee.
I would recommend you ask questions about things that may have impact years down the road. For example, what is the troo