I'm no expert but I'd say just go with the 3.2 upgrade and wait for the third party readers to be "fixed" for this firmware build. You can downgrade the firmware to 3.1 if you want (I don't think preventing the update while registering is possible), but personally I experienced database corruption after re-sideloading some books while on downgraded firmware. Sure, it wasn't necessarily the downgrading that caused corruption (I suspect some Calibre plugins) but fact is I haven't had any issue since I re-upgraded to 3.2. I think it's just a matter of days till we'll be able to install both Coolreader and Koreader on 3.2. In the interim I prefer to spend my time reading, rather than doing repeated factory resets and reinstalls.