My real workhorse seam ripper is a palm size 4" X 1.5" Wahl battery operated trimmer I picked up years ago at Sally Beauty Supply. They were $11.00 then. if they still carry them who knows what the price is now, but I expect any small trimmer will work. If you've got one of those torture devices marketed as Epi Lady try it, it might work fine. Separate the two pieces of fabric so you can see the first thread in the seam and then just lightly lay the running clipper blades on the seam thread. Don't Push, let the clipper do the work, you can unsew a mile of stitches in zip time. Added benefit is one side of the fabric will have one long thread you can pull away, the loops on the other side are nearly non-existent.
Gratitudes for the day:
My bone china Under Gardener coffee mug
My new sewing machine fits in the table recess where the old machine was (that is more along the lines of a miracle...)
On-line friends of long standing