iGrade is automatic control of scraper height.
SWP+ is manual control by operator looking at something like a vertical "lightbar".

iGrade is $4000 above SWP+ (which I can't remember exactly).  If you have the 2600 and two RTK receivers, I think it will cost you a little over $10000 to go to iGrade.  That price would include some harnessing to the scraper for the second receiver, but then we made our own mast to mount it.