SF3 is just on the receiver on the roof.  Nothing to do w/ the display. 

It's pretty good unless you're trying to strip till on the same strips year after year. 

Prices have really come down lately, I've seen 6000's WITH SF3 ready on it already for $3k or so. That's less than it would cost you to buy the SF3 ready for a 6000. You'd be money ahead to sell the SF1 6000 and buy the SF3 ready 6000 in that case over upgrading yours.