Anything that needed to be installed via a .bin file probably dumps stuff into the rootfs, in which case yes, you need to reinstall it -- because downgrading involves doing a system update with a full image provided by Amazon.
On the other hand, it is easy to chain install hacks using the new
MobileRead Package Installer.
Also, any configuration contained in the /mnt/us/* folders, where linkss/python/usbnetwork/etc store all the binaries/libs/conf/etc will be retained, as will KUAL and extensions. So it shouldn't be all that much of a bother.
