I don't usually brew many beers above 1.060, but generally speaking I'd start using extract once my mash tun can no longer accommodate the grist at 1 qt/lb. BeerSmith makes it pretty easy to figure out.
The Fiesty(sic) Goat Brewery est. 2007 & Clusterfuggle Experimental Ales est. 2009
Planned: sLambic II, Flanders Red II, Orange Blossom Mead, Fat Man Porter
Primary:sLambic I, Janet's Brown
Secondary: Toasted Caramel Port, Flanders Red
Kegged: Hefeweizen, Centurion Falcon IPA< Dark Saison
2013 dump volume: ~2 gallons