Okay, I can see why you would struggle. If you wait a few more years, does that make it a lesser chance of the surgery working? She can wear the hearing aid now and function okay? Ask the specialists about the scarring issues and such, for possible repeat surgeries as she gets older... and especially why they changed their recommendation of waiting.
If she can wait some more years and still be fine, then I would say wait. If waiting would hinder her ability to have a positive outcome in the future, then I wouldn't wait... But from what you say, I would likely go the hearing aid route for now. I wouldn't use the summer fun as a decision factor.
I would do a lot of prayer and research on this.