Ok, here's what I did for me to get used to ar10 a lot quicker.
Convert your favorite ar9-9.5 nomod maps to ar10 in editor and make a collection out of those. Have around 30+ maps to have some variation and keep playing those regularly. This may come at a cost in that your reading in ar9 will probably look like ar8 to you (at least for me it does). If you really want to go through my way (which I kinda don't recommend since my ar9 reading isn't as good and consistent as before), then do nothing but ar10 for a month to get used to it, then if you feel comfortable enough with it, start playing with HR.
Your case seems to be like mine regarding reading ar10 first and then learning HR. In that case, after you do learn to read ar10 comfortably, then I'm assuming you won't have too much of a problem with the OD (which wasn't for me).
So yeah, as you can tell from my performance graph, I stagnated around 1.5k for about a month due to the fact i was in intense ar10 training
Then I got around to doing some HR farming and ar10 officially became my main AR.
I would advise that you don't completely neglect ar9 and play it as much as ar10 or even less, but I'm sure the process of getting used to ar10 will take longer...
