My personal experience.
On my 5.2.1 firmware there where
- jailbreak 1.2.N
- simple_usbnet_1.1
- libfreetype 6.8.1
- launcher_1.2.2
- reading timer
- skipstone browser
- kindlet-jailbreak-20120509
- jbpatch_2.4.0
- simple screensaver 1.0
The 5.3.2 update did not apply.
I first unloaded reading timer (to restore the filesystem) and then the launcher. No luck.
Then I uninstalled the simple screensaver. No luck.
Then uninstalled libfreetype. No luck.
Then uninstalled jbpatch.
At this point I could upgrade to 5.3.2. Well: IMHO the new interface sucks. Buttons, toolbars and menu bars looked much better before. Maybe I just need to get used to them. On the other hand it seems snappier.
So I could upgrade with jailbreak, kindlet jailbreak and usbnet installed.
The USE_ALT_FONT file was still in place and I could use all my additional fonts immediately but - for example - Linux Libertine was garbled. I installed again libfreetype wich seems to work well.
Then I installed the new JBPatch - which by itself doubles the pleasure of reading and is a
conditio sine qua non before upgrading - and it works smoothly.
The Simple Screensaver also works.