Have never used a straight seam. Always a bias. My thought is tension on a bias would be less than a straight seam. I agree with Peggy,,, I always try to purchase yardage so I can use a solid piece, but sometimes it doesn't work out. My bindings are always cut bias and I only use a 1.25 cut, so its very narrow.
I had never even heard of using a diagonal seam on a border until this discussion. I don't think I've seen one in a quilt either. Apparently I'm not paying attention! It makes sense that it would be less noticable on the diag.
I hardly ever have yardage and piecing the borders doesn't bother me. (Piecing my pieces is common here if I am short fabric.) Even if I have yardage, I have a hard time cutting that long strip along the selvage. The only time I do that is if I'm forced to because of a stripe or directional fabric. I think it is just stubbornness on my part.
I always piece my bindings on the diagonal so as to avoid bulk when it is folded.
Thanks for this discussion. I'm always learning something new and will have to start considering piecing my borders on the diagonal.
I'm with PQ on this one. I have never noticed if someone pieced a border together. I am not much on wide borders of one fabric, so I guess that is why I haven't run into this problem. I really prefer borderless quilts or quilts that have been made out of pieced blocks. I always use bias and use folded 2.25 to 2.5 inch fabric for my bindings, once folded that brings the actual binding to about 1.25 and I always finish with a forty five inch diagonal seam.
I do know that if something is quilted heavily enough as in my Hawaiian quilt the seams disappear and the quilting takes over.
I use a diagonal seam and the reason I do is because I find my eye isn't as drawn to a diagonal seam as it is to a straight one. JMHO.