hray

My Brother VQ3000 won't go to a stitch length of 0; the lowest it goes is 0.2. So I always drop the feed dogs for FMQ.

oldmanquilts

There's no reduction in "wear and tear" as the entire mechanism still moves the parts through the entire range, except the lift is reduced in the FD down position.

The "feed dogs up" allows for the sandwich to be compressed as the needle is on the upstroke to eliminate flagging and dropped stitches. This functions much the same way as a hopping foot one might normally use. The drop position is actually for darning.

Yes, a longarm doesn't have feed dogs but it controls the layers with a "hopping" presser foot, much the same as feed dogs up.