I don't have a copy of 2.10 yet; however I tried to get things to work on 2.9 and this is what I was able to get from that effort (using NA maps):

The map version that you are *forced* to download (basemap, timezone, and NA map) at this time is 2015.20 (for comparison current rev is 2016.20); maps are installed to the following locations:

<ID>/Documents/basemap/gmapbmap.img
<ID>/Documents/gmaptz.img
<ID>/Documents/na_complete.img (I chose to d/l the entire NA map)

The forced download also includes the 2015.20 version of the InstaSearch D3157140A.SID.

Extras you can d/l for free include photoReal Junction View, 3-D Buildings and Landmarks, and Wikipedia--these are installed in the following locations:

<ID>/Documents/D3191140A.JCV (this is the 2015.20 version of SplitScreen Full JCV view)
<ID>/Library/sdcard/Garmin/gmap3d.img (like the other maps, this is also 2015.20 version)
<ID>/Documents/Wikipedia_GPI.gpi (Wikipedia)

Although not free, you can get Panorama View 3D to work by simply copying the appropriate DEM file (in my case I copied the NA one, gmapdem.img) to this location:

<ID>/Library/sdcard/Garmin

One other bit of good news--looks like the Safety Camera feature (i.e., speed and red-light camera locations) is still there, as you can view the Safety Camera Locations via plist hack of the settings_general.plist file.

Now for the bad news--unfortunately I cannot get Traffic, Urban Guidance (routing using public transportation), and photoLive Traffic Cameras to work, even after messing around with various plist files. In addition, it would appear that trafficTrends is no longer a purchaseable option--it's not even listed in the Extras section; I'm guessing this may be due to the fact that there is now a feature called myTrends (for which I had to hack the settings_general.plist file in order to view the various myTrends-related settings you can play with that don't show up by default).

Even more bad news--like others before me, I cannot get 2.9 to recognize the latest Garmin map files; if I try to open 2.9 using maps that were not d/l and installed directly via the app, the app will act as if you don't have any maps installed and ask (i.e., force) you to d/l the maps from the Garmin server--you can't simply ignore the prompt, as the app will just not progress any further. I think what may be preventing the app from recognizing custom maps is the presence of what I believe to be unlock files found here:

<ID>/Library/sdcard/MapUnlock

I see these files:

3471_1_0_0.gma
3471_2_0_0.gma
3471_1_0_0.unl
3471_2_0_0.unl

I'm guessing that they are for the NA and 3D maps I d/l via the app; I tried deleting these files and then manually copied the 2016.20 files (NA map, 3D map, JCV map, SID) to the same locations--the app still asks you to d/l maps before it'll allow you to use the app.

Even if there was a way to be able to use custom/latest maps on Garmin 2.9 and above, I'm still a bit bummed about not getting Traffic, Urban Guidance, and liveTraffic Cameras to work on 2.9--all of these work on 2.2, albeit with a few bugs that you can work around. Hopefully someone smarter than me can figure it out...