I have had my y6a for a month now and I feel comfortable giving my opinion on 3rd rails quality. I think this is the best engine I have ever purchased! This is the smoothest running engine I have ever owned and the attention to detail will make your head spin.
I put my lionel class A, y3, y6b, and the 3rd rail y6a on the same track and using the lash up command I was able to see just how much difference there is between the engines. I love all of these engines especially the lionel y's but 3rd rail takes the win for detail, operations, and sound. The y3 and y6b are very comparable in running ability since both are equipped with odyssey speed control but the y6a will run at such a slower and constant speed it makes double heading them hard ( I think the speed step can be changed to fix this?), I especially like the optional 4 chuff per revolution that is equipped on the 3rd rail engine and after having that feature I didn't realize what I was missing since it makes the engine much more realistic. This is all just my opinion and observations from running my trains. I think MTH, Lionel, 3rd rail, and others make fine products so this is NOT a brand war.
What are your thoughts?