I got the 3.1 update done earlier this week. For me it took about 2 days, and no battery modules were required. The dealer had a loaner, so that was good too. My service advisor was telling me that she has a good long list of cars needing updates, and she gets calls daily asking about it (she said some people are "mean" on the phone - not surprising, I guess.). Other dealerships in the area have wait times of several months, so people are calling around. She said most cars don't seem to need any battery modules, but they are trained to handle it when it does come up. As for new/different behavior, there is all sorts of stuff. Some subtle, some not so subtle. And having new software in the vehicle seems to unlock new functionality in the app as well (you can see door open/close status, for example). I am still playing with it and discovering new/improved stuff all along. Nothing negative yet - it is all good. After a few weeks, I will write up a new thread describing all of the things that I have found that are new. One thing I discovered just this morning was that from the app, I can search for a destination and send it to the vehicle. I haven't actually tried it yet, but this would be huge. It used to be that entering a destination in the car was a huge pain in the *** - you needed to know an address, and using voice commands was spotty at best. The old car software could do route planning with charging stops, but you needed to keep a close eye on it, because it would do dumb stuff like pick L2 chargers when there were DCFC in the area. So that's something else I want to play with - see if route planning is improved.