The 32GB card I was using in my Q7 died so I decided to install Mer0.16-5 on the Q7. (Thankfully MicroCenter has a lifetime warranty on the SDHC card.)
WiFi works well!
The Q7 doesn't have a problem remembering my WPA2 password after a reboot so that's an important difference between the two devices running Mer. My Q5 has a known hardware clock issue that is still present under Mer so that may have something to do with it.
I've added some more information to the WPA2 section at http://wiki.maemo.org/Mer/Documentation/Installation
to reflect my experience with the drivers for the Q5 and Q7.
As far as applications go, I could not get maemopad to install and run even though it's listed as installable via App Manager. Maemopadplus seemed to install but it did not appear in Extras--just two blank lines--so I could not start it up. Finefm and gpe-filemanager installed without a hitch.
I could not get FBReader, Panucci, or Mirage to install using "sudo apt-get install package_name" and I was disappointed. I'm sure the library of installable apps will improve over time.
Tear worked reasonably well and it seemed faster than on the Q5. I was able to use Gmail set to basic HTML view. The scrolling interface was great.
The Bluetooth Manager did not recognize the BT dongle that eletroworld ships with the Q7.
I was not able to get Mer to recognize an external USB keyboard. Also, after connecting a Vista laptop and the Q7 with a USB cable, the laptop knew the Q7 was attempting to connect but could not find a driver to access it as a USB drive.
I tried to load X Terminal, Tear, and App Manager at the same time but the OS wasn't up to the task. At best, Mer 0.16-5 can run two of these apps at a time.
Many of the above issues may be resolved with some tweaking but, for now, I'm moving back to firmware 4 once I've gotten a replacement 32GB SDHC card.