the kobold will start out much weaker than the lizardman (which "feels" right -- it's just a kobold) -- but by 5th level, the kobold is a 5th level character, a legend among kobolds
because I would never let one of my players play such a race, especially when everyone else played a normal PC race. Then I said I changed my mind and wanted to play a delver instead. Now that I haven't heard of them since I know the DM isn't completely bonkers and I wouldn't mind trialing out if I had the time.