Any time I hear of a methodology that encourages people to work lots of overtime I cringe.
Me too. Scrum doesn't encourage overtime. No one tells the team how to meet their goal... if they decide to work a weekend to make a goal, they can choose to do so. Otherwise, they go home. Their decision. The team agrees to what is going to be in the sprint.
There appears to be a pretty serious misunderstanding about Scrum here. Many of the most vehement objections that have been voiced don't have anything to do with Scrum.
A: dot dash
T: dash
AT: dot dash dash
W: dot dash dash
wouldn't work.