You're very welcome!
The martingale is not advised for tags and everyday wear because it can be a choking hazard. Since it's designed to tighten with tension/pressure, if the dog got it caught on a fence post, cabinet knob, hook, crate, etc., and started to struggle, you can imagine that the situation could get serious very quickly. I use a standard buckle tag collar, but the safest bet is one with a breakaway mechanism (also helpful when your dogs are playing in case one gets a tooth or leg caught in the collar—maybe a remote possibility, but still worth considering). I also leave the martingale attached to the leash so I don't ever have to worry whether I left it on Sweep unsupervised.
(Not trying to make you paranoid, I promise!)