it sounds like your dealer wants to lower the bike simply by taking some preload out of the shock and sliding the fork’s up in the clamps. It would just be a little bit softer, so it would sit into the travel a little further. If you only go 1 cm it’s going to be a very small change and you may not even notice it. Since we are only talking 1 cm, have you sat on the bike with riding boots on? That can make a few mm of difference one way or the other, and you might find yourself more comfortable / confident in good riding boots as well. There are always seat modifications too. Given how light the bike is and how close you are to being flat footed, I’m sure you will be fine.