As Bryan suggests, if you have never used a double hose you should not underestimate the difference. I have told people this and it was not until afterwards they understood. Not more diffucult but different and you should learn that in the pool.
For example, the double hose does not like to be surface swimmed on your back. For two decades with single hose I have surface swimmed on my back. With a double hose it free flows constantly, so now I tuck a snorkel (sometimes) in my belt and surface swim face down using the snorkel--as was done in the old days and as actually I was taught. Sometimes the instructor knows best.
Try it out in pool and then progress to an open water but controlled area. The chlorine is not going to hurt anything a few times.
James