Let me just check, if I understand the essence of this Topic because I am not a native English speaker.
The 600 offers less finer steps in changing the R(ecovery)S(peed) than the 800 does? The 800 in addition allows for a bit slower AND a bit faster RS? So, if you want to use very small coils that allow for a slower RS or large coils (vice versa) then the search results with the 800 are likely to be a bit better?