It always amazes me that so many people are willing to dump aggressive chemicals (i.e. advertised as strong enough to dissolve carbon), into their engine for 'cleaning' intake valves, without ever knowing if the stuff is successfully working, or if it's even needed in the first place.
IMO the only acceptable way of addressing this intake valve deposit issue is by using an approach that very few people (or shops) are willing to spend the time and effort to do. It starts by using an inspection camera to examine the valves and determine the level of deposits that are actually there. Then, if (and only if) a significant amount of deposit is found, action (chemicals, walnut blasting, ...) can be used to address the problem. And if chemicals are used, I'd be doing an oil/filter change after the process has been completed.
I haven't found any reports yet of intake valve deposit issues on our Skyactiv engines - maybe some do exist and/or will be showing up in the future. Time will tell on that, but for now checking for deposits in our vehicles is not currently anywhere on my list of things to do.
But if you want to help pay for this stealership's next big boat, I'm sure they will be very pleased to accept your contribution. And you probably don't have to worry much about chemical damage to your engine, because their 'cleaning process' is probably nothing more than pouring a bottle of fuel system cleaner into the gas tank.