Thanks for the comments, questions and more... a bunch to answer so I apologize if I seem to just hit some highlights.....
Battery life -- even today's most modern phones can get pulled down quite a bit pulling data (killed my phone many a time watching netfix at airport with delayed flights), its never an easy answer. So yes, if you go nuts on wife/Bluetooth it will take a toll on the battery. While its a great use - heck watched the last hour of the Daytona 500 one time on my 6R - it not the primary purpose. With the wifi/BT off, if you put your radio in sleep mode or even power it off between runs, you can get a day from it and more. Boost it on the cradle between runs if you can, I actually don't unless I really need to - it happens. Dakotah has run many long nitro mains with the 6R, sometimes back to back with a short break... so it can do it. Finally, my last trick -- I have used one of those cell phone power backs plugged into the 6R. Had a driver at a big race, realize he forgot to charge his 6R over 2 days and right before the A main realized it was on 2%. We plugged in the power back, put it in his pocket, he won the main and had from 30ish%(forgot the real #) on the 6R after the race.
Wheel - the small wheel has an overall diameter similar to futaba and sanwa, but the wheel/foam size is a little different, I think.
Boot time - it is a minute 30 odd seconds to boot up... in the grand scheme of things, its something you get used to. If you have my radio all the way off. I turn it on 2 minutes before the race before me ends, not 30 seconds. You get used to it. But 95% of race days, once I start my first practice for the day, the radio stays on, and put it in sleep mode between runs.
OS locked... the development process of the 6R happen before I came on board with Spektrum, while not a software engineer, my guess is that there was a concern that if everything was open.. it would be possible to update something, down load the wrong thing, basically kill the operating system in a way that we (a r/c radio seller) would not be able to fix. Easier to lock it to a state we know is working. Strictly my opinion.