Just curious. I was a small city FF in a large urban county. Other than the all too frequent major brush fires, hydrants are a plenty here. The tenders/tankers here could easily be converted to milk trucks just by taking off the lights and siren. My curiosity then is why the need for these huge tankers with 6 man seating, foam systems and 2000gpm pumps.
My dislike for quints is primary based on the amount of time ours are out-of-service. This primarily appears to be a weight issue with the constant stop and go of urban responses. The wear and tear on the trucks is terrible. The other is that adaptability. With 3-man, or even 4-man units, acting as a truck and engine company is nearly impossible. If within your first due you catch a worker, is there another unit that acts as a truck company?
Here's our 3000 gallon Pumper/Tanker, with a 6 person cab. If we get a fire call in our rural (non-hydranted) area, the duty crew will "jump" from the Engine to the tanker and respond. It's like having an Engine with a 3000 gallon tank! It carries most of the things an Engine carries accept it's also got a porta-tank on the side. Hope this helps you understand, Jay. Stay safe!