I think I will use this method in combination with some RibbonRail type guides I plan on cutting up out of some thin scrape alum 'street sign' pieces I found at the metal scrap yard.I don't know if this would be of any help, but I make my flex track longer. I slide one rail out of the ties halfway, then slide a rail from another piece the same way into it. This staggers the joints so that fighting the end radius is removed. I have done this so far with 3 pieces so that I basically ended up with a 9 foot piece of flex track.
I kind of like the RibbonRail type guides, and I have a good router to make some up,...maybe even a few longer guides than those they offer.