While yes you can do some things in IUpgradeable -- you still need to think thru how it will be used - for example - what happens if there are multiple portals - say for example you have 2 portals - does you module get put in admin of both - also what happens if you add a new portal.

iUpgradeable ONLY fires as the module i being installed onto your hosting - if you add a new portal or sub portal it wont automatically fire. As such in many cases - some code that fires the first time a module is displayed after it is placed onto an actual web page is the best approach.

Just me 2 cents -