The older one still works very well, but doesn't have the neat little "gameboy" controller
Check out andersonfordmotorsport.com for the differences. The new one is a better unit for sure, but for $425 this one would be hard to pass up. I think the new ones are like $899. You can also have this one upgraded at a later date.
btw, I'm not sure about that guy posting the PMS, never seen the name