There's a Ghost Bear Khan famous for piloting a Fire Moth her whole career. Familiarity and experience with a particular mech is something that BattleTech categorically fails to acknowledge. Rickard could very well be significantly better at piloting a Firestarter than any other mech, and be less likely to make a mistake or go somewhere he's too exposed, where the physical durability of the mech is less important and less useful.
It's more interesting - and better writing - to use information already presented and determine how or why that came to be than it is to force something into an efficiency cookie cutter shape.
The difference is the Fire Moth goes fast enough to survive and can easily mount weapons that reach more than 270 meters. She was also know IIRC to swap between configs though mostly sticking with the ERMLs of the D- a weapon that hits almost as hard as a standard IS large laser, carrying the weapons load of a medium mech.
Your last sentence absolutely neglects the ONLY mech we ever had him piloting in fiction was a ATM Shadow Hawk IIC. The Firestarter was just his MWDA fig/dossier- a mech that has 6 regular flamers and a Defiance ERML . . . and 'walked off the assembly line before the fall of the Star League . . .' before the Cats took it as salvage from the Dracs. Guess at some point it was restored to SL stats w/ its ES frame.
But in the final FWL rebirth arc in the MWDA novels he is leading the Spirit Cats on their invasion of Marik and singles out a Legionnaire that is sent against the Cats in a spoiling attack. He uses the speed, maneuverability, and flexibility of the Shadow Hawk IIC to take down the Legionnaire with minimal damage- no comments on it being a new mech or unfamiliar or anything along those lines. It is a very well written, letting the reader picture the two mechs moving against each other in battle quite easily.
The Shadow Hawk IIC is not the 'best' mech they had in their inventory at the time- one of his subordinates pilots a Nova Cat and they already had the material backing of the Sea Foxes above Marik. It is instead a good average medium mech rather than some uber machine.
