erm... who actually *types* in the address bar?
all the sites i regulally visit are saved as bookmarks, (porn, or otherwise), any other site i view is either an emailed link (clickety), google search result (clickety), or a non-linkified url in a web page (ctrl-C ctrl-T ctrl-V)
How often do i need to type in a url?
I can see that people who deal with business cards may do it on a regular basis, and web addresses need to be recalled from memory while using seldom used (or unfamilair) machines, but that is not something that i deal with very often.
As for pr0n mode, unless you are looking at stuff in the *same session* as the work/wife/kids are about, then setting FF to delete all history and cookies on exit, gets rid of a lot of the risk (and ability for other websites to track you - i remind reg readers that flash apps can leave cookie like footprints on your system as well - i suggest BetterPrivacy FF addon)
I can see why porn mode might be useful, but it still doesnt offer any functionality that didnt already exist (other than not arousing suspision by having an empty history - thats quite a good one, damn).
Bookmarks will still be an issue though, in which case either seperate browser (FF portable?), or for your regular haunts, actually use the address bar. (which will be forgotten about at the end of the session) No porn mode required.
The awesome bar is useless, but only actually annoying if *other people* are using the awsome bar to track what you are doing (accident or not), in which case just make sure there are no tracks to find. (this should be on an entrance exam to read El Reg)
my personal way of dealing with this (in the event of laptop theft) is to have an sd card living in my lappy with a truecrypt volume on it, loaded with portable apps. (good password, force dismount blah blah) It also makes fixing other peoples computers a lot easier, not having to access the internet with a toolbar/virus laden IE (yes, i know viri can spread via such cards/drives)