OK, the officially stated reason for the creation of ProtoMechs is to save resources, to test this statement I decided to roll to the RAT for ProtoMechs and use the results as the basis for a 'Mech. My rolls where:Satyr, Roc, Roc, Hydra, and Harpy. And my resulting 'Mech weighed 25 tons, moved 5/8/5, has 3.5 tons of armor and is equipped with: Light Active Probe, 2x ER Medium Lased, SSRM4, ERSL, mPL, and a machine gun.
My conclusion: Well my 'Mech kind of sucks, dropping the ERSL and MG for 1.5 tons more armor would help. Secondly there might be something to this, as long as you don't design your ProtoMechs to compete with BA, which it seems like just about all the designs I rolled do.