Here's how I see it .. in april next year support for 11.10 will cease, so I'd be happy to stick with 11.10 until I hit a problem, then rather than sort the problem, I'd use that as the opportunity to upgrade.
Sorting any problems will take time, as will installing 12.04 .. but why do both .. which you WILL have to do eventually
If you say what you considered "awkward" whilst installing 11.10, we may be able to mitigate it somewhat for 12.04 by keeping copies of some of the 11.10 confg files such as keeping a copy of fstab (for reference), and the Ushare config file, and in my case but not yours, I'd also keep a copy of the /etc/openvpn directory, etc.
On a system with problems, I'd go for a fresh install rather than an upgrade of the OS .. but as I said, I'd take copies of certain files to make it easier .. upgrading a system with problems is liable to end up with a broken system with a higher version number
.. besides which, I'm a fan of fresh installs anyway.
You'll also be surprised how much easier printer configuration with the HPLIP Toolbox is than without it .. and there's no way to get it working on your system with 11.10 and the upgraded hplip you need for your printer.
Anywho .. If you'd prefer to try installing hplip 3.12 as a fix for your broken hplip 3.10 .. theoretically it should uninstall 3.10, then install itself .. let me know and and we'll go from there .. but as I said, I'd give serious consideration to taking this as an opportunity to move to 12.04 which will work with your printer/scanner "out-of-the-box"