I have just started building strings and B500 is hard for me to twist, the larger strand/bundles seem to give me fits. A person can get spoiled building D97 strings…the material is easy to use and wants to twist nicely.
As for endless loops, I have no experience with that process. There are some very experienced string makers on here i.e. LBR that could help you out, not sure if he makes endless loop but from what I understand he makes amazing Flemish strings.
A friend of mine says TS plus can be inconsistent with the wax content and he has stopped using it, he switched to D97 and loves it. He now uses it on all the bows he builds.
Josh