You can use a short 4 or 5' piece of hollow core to achieve a 100% connection.
I'm a big fan of splicing hollow-core GSP braid--in fact I've switched to it. When you use it to splice two pieces of braid, do you serve the two ends of the splice or just glue them? (What glue do you use?)
If its colored line especially, I use the JB two part glue to strip off the coatings then glue. However there are many different methods, some that use glue and some that don't. The method that you have confidence in and that can be completed quickly is ultimately the right one.