Yep. I've been patiently waiting for this update so I could do just that.Is it relatively safe to use emunand 7.x to purchase eshop games now or could a future GW update invalidate the current emunand and lose all purchases? I don't think a re-format of emunad is needed from b1 to b2 but some people are doing this anyway. Or if needed, can I recreate emunand and re-download the eshop purchases since it is to the same 3DS? I suspect this process may invalidate old save game data on the SD card.
Your eshop purchases are tied to your console's unique hardware id, which should be the same regardless of whether you're on the system nand or emunand, so the worst that could happen is that you have to redownload them.
You're also right about not having to reformat your emunand to upgrade from b1 to b2.
As far as I can tell, everything that was working on my 6.3 emunand is still working on 7.1 except for the Youtube app, and I don't think a reformat would change that.
Also, a friendly reminder:
If you haven't updated your emunand yet, be sure that you only do so via System Settings whilst in Gateway mode.
If the firmware version isn't prefixed by "GW3D" in System Settings, it's not safe to update. Just be careful please