I have numbers this time. A 10 research team corvette (310kt) costs 3035, 5790, 3675 to build. It costs 103, 196, 124 to maintain. A 7 research team small transport (300kt) costs 3425, 4150, 3825 to build, but it only costs 23, 37, 24 to maintain. I can maintain at least 28 research labs using transports for a similar cost of maintaining 10 research labs with a combat hull. This is why I use transport hulls for research vessels.
