Just noticed this thread...
To be honest, yes, you're pretty much right (save the arguments that nigel has mentioned above) - the main difference as you "move up" tends to be in the area of picture quality rather than sound.
Analogue outputs are a different story, but if you only ever intend to use the digital out then I sincerely doubt that you'll notice a huge difference between a £100 player and a £1000 player (IMO anyway - I'm sure there will always be people who "can"

)
Hope this is of some use to you... good luck!
K.