@jonest: I assume you run TC, correct? If so, I'd start with profile 5 and lowest motor timing (e.g. "oooo" insert) and then increase from there and check motor temperatures (they should be below 90°C).
@jamesarluck: yes, software is the same on both SXX versions (80900 + 80950). Main difference is the better cooling on SXX TC spec between the two.