Hi all. I've been working on my first MYOG project, a small Dyneema X summit-style pack inspired by the 2013 MLD Newt. I've done all of the seams with a basic flat seam (with roughly 1/2-inch seam allowances) and I'm now wondering what's the best way for me to finish and seal my seams? Is it necessary to do a flat-felled seam, or could I just do a top-stitch (which I understand does add some strength to a flat seam, but not as much as a felled seam would) and then apply seam-tape/seam grip.
I initially did flat seams because the pictures of the MLD Newt make it look like it has flat seams, but then the description on MLD's site says that "all seams are double stitched". In the absence of a second line of stitches I thought this meant that they simply go over the original stitching with another line of sewing but from what I've read this could actually make the seam weaker because it introduces a new set of needle holes. Are more needle holes likely to significantly compromise the material's strength? If so, what does this mean for areas where I've unpicked and re-sewn?
Finally, I've got one seam that has about 8 pieces of fabric going into it (shoulder straps, zipper tape, etc.), making it really fat and stiff. Any ideas on how to best to seal it? I think I should be able to sew it flat and tape it but any other suggestions would be appreciated.
Many thanks in advance!