The pain of add-ons ... now plugins ... has to be tolerated via the 'moodle march' through version 2.4. At that point, IF the plugin has been hosted on Moodle.org's site, when checking updates, Moodle will have a link to plugins that need updating. Have used. Works as advertised, although the warning given is one that should make one take pause - recommending the site be backed up before proceeding. I'd vote for some kind of tool where one could take a 'snap shot' of the DB and the mod/block or whatever is being updated and having the ability to 'roll back' if there's an issue (know that sounds simple, but it's not).
As far as making the Moodle March and add-ons/plugins ... thats one of the research items and pre-march prep. Before the first step ... that of 1.9.19+ to the 2.2.highest, one manually installs the same add-ons/plugins in the 2 before migrating. When the migration takes place those tables should be included. Don't do that ahead of time and Moodle will always complain about a discrepancy and wants admin to 'fix'.
If one had many sites to maintain/do, would encourage the use of command line. Can and have, put together a little command line bash script that steps through the process. 15 sites in 1 hour ... with backups before the upgrades and after.
Have another that's dangerous in that I have to remember to pass the version desired to upgrade ... ie, site is 2.4 and wanna take it to 2.5.
Too bad there is not a scripting place to share here with ability to view the actual code (lines in batch file/bash script) being shared.
Anyway ... the other thing I've learned about add-ons/plugins ... exercise caution. Decide if it's worth the trouble one might face during upgrades.
My 2 cents!
'spirit of sharing', Ken