Alright, fired up the upgrade package - good news for those folks running Bell version of the Optimus LTE - works awesome. I'm running it unlocked on Fido and after letting the OS settle for a few minutes and uninstalling all the AT&T crapware sh...
The Nexus 5 (and most phones and tablets, I assume) that have official Active/Quick covers use a magnetic sensor. All you really need is any flip cover (I got mine for $5 at a flea market), a flat craft magnet and a little double sided tape.
Someone really just needs to put up a sticky that says you can't flash custom recoveries from ICS.
Of the two you've chosen I'd go with the Quadbeat 2s. Sound good and they were designed to work with the chipset in the N5.