I haven't owned a new Weller, so I can't comment on those. However, for soldering SMT stuff, I use 500F (measured at the tip), and for bigger stuff like D-Pak FET packages, I'll crank it up to 550F. If I'm doing larger components on thru-hole boards, sometimes I use 600F for quick soldering.
Soldering temperatures for SMT parts range in the 260C to 300C (500F to 572F) range for ten seconds maximum. Since I like my stuff not to be abused, I try to stick to those ratings. The D-Pak stuff normally has the higher 300C soldering rating.
IMO, 650F-700F is too hot. I used to do that, but when I lost a couple of parts, I started paying more attention to the actual component ratings. When I was doing mostly thru-hole stuff, the temperature wasn't nearly as critical. Other than some diodes, LED's, and other sensitive parts, you'd probably get away with 650F for a long time if you are only doing thru-hole work. When I was building my flickering firebox modules with four thru-hole LED's, I was losing a lot of them working at 600F, I dropped it to 500F, and I haven't lost one since.