Terry wrote:

(...)

mmmm.... doesn't it depend on how often the saw is used? Drag on the
teeth will dull the blade, yes. But blades aren't horribly expensive,
and the application is once in a blue moon. Wholesale Tool has a 21"
blade, 4tpi for $6. Others are up to $20. If each cut ruins two
blades, that's 12-40 bucks for the cut. Which is only going to happen
once in a while.

Plus, power hacksaws that lift the blade on the
backstroke are in the minority. Many didn't.

http://www.youtube.com/watch?v=6BvhZxfMPDU
http://www.youtube.com/watch?v=fh8QcXLSZGg
http://www.youtube.com/watch?v=Wcgm5iucqK4
http://www.youtube.com/watch?v=apb6SwhGrIg

(...)

--Winston