I will only wear a strap next to my kilt. Once you've ruined a favorite kilt with a chain, you're not likely to wear one anytime soon. I usually make my own using the mystery weave (google for a link with instructions) or hand tool and stain the strap to match the sporran. Recently, I used a flat leather strap and attached to the surface of the strap and dressy chain. It gives the "bling" of a chain with the "kilt kindness" of a strap. I'll try to post some pictures, but it's really pretty simple to rivet the chain to the strap every few inches using decorative rivets or conchos. Just be sure the back side of the rivet that faces the kilt, is perfectly smooth. I cement very thing leather to the back side of the stap, over the rivets for added safety.
I have found that this type of strap also slips less than a chain.
YMMV
Semper Fi,
Keith