These only have advantages. They sound the best (They have a bright and direct tone), they are the cheapest double ball strings, they last long. Never ever head one break on me in years of playing headless guitars.
They fit very easily, as where things become very tight with other brand strings, it seems these are just a tad longer....
Even if I have string adapters to use on a headless guitar, I always come back to using these strings... The biggest advantage maybe is, that you can re-use them easily.
You don't need to throw them away after you've removed them from your guitar (for fretboard cleaning, for pickup swapping...). Just store them safely and you can re-use them (no curled ends like normal strings wich have been used)