I was looking for info about ships last night and I found the Alioth.net website with all the old games ships etc. It is interesting the changes that have happened to some of the ships over time (both real and in game). Take the Anaconda:
In Elite it is described as a freighter. In Frontier and FFE it was 'you've decided against bounty hunting or piracy as a way of life.' and 'primary occupation is going to be trading, with perhaps a little short-range taxi service work' so again it is a freighter or maybe a coach. But in E:D it is much more versatile. You can have a decent amount of cargo, yet now have a massive amount of firepower to back it up with. So we have gone from something you used if you were just shuttling cargo around to a formidable weapon (in the right hands).
The Python is another trading vessel in Elite, described as 'slow and ponderous' but in Frontier it moves up to being a 'medium freighter but flies like a large fighter'. And of course in E:D it maintains that ethos, maybe slightly heavier on the fighter side.
The Cobra seems to be one of the few that have maintained its original role as a trader/fighter. Across all of the games it is advertised as such. The Viper has done well too, still considered to be a light fighter.
Just some ambling thoughts again, sorry!