Soldering irons: single-watt vs. temp. control

[Gyro]

You guys seem to run your irons rather a bit hot. I use 320'C (verified) on my TS100 with Kester 63/37, especially with smd. I used to use a PT6 (310'C) or very occasionally a 7 (370'C) on my old weller TCP. Joints flow without needing excessive dwell time. Are you sure you're not burning the flux off too quickly?