I've been a casual Portableapps.com user (i.e., not a "junkie") for a couple of years. After reading this article, I got curious and spent about two hours installing and trying to use LiberKey as I would PAP. Here's my own take on PAP vs. LiberKey...
What I like about LiberKey:
There's an option to auto-install important updates. In PAP you have to manually select Apps / Check for Updates. I wish there was a way in PAP to configure it to auto-update all apps even when my PC is sleeping, just like what we take for granted in iOS and Android.
The menu search functionality is superior to PAP because it also searches the app description. In PAP when I search for "outliner" I should get a match for The Guide, but I don't because PAP only matches against the app title. The minor downside is that there's a higher chance you will find false negatives in LiberKey.
App installation/update appears to be more reliable. In PAP whenever I update about a dozen apps or more in one go, it almost always crashes on me (I'm using v11.2). This, compounded by the fact that PAP has no automatic update mechanism, makes updating apps a big chore. I haven't installed that many apps in LiberKey to say whether it's more robust, but so far so good.
What I like about Portableapps.com:
The menu interface is faster. The first thing I noticed when I launched LiberKey was how sluggish it felt compared to PAP. I dunno, it reminds me of one of those Java apps from back in the day, or a ported Linux app that runs on top of GTK or something. LiberKey still felt cumbersome even after I disabled all animations.
It consumes little memory. I was shocked to see that LiberKey uses up about 3x as much RAM as PAP (15 MB vs. 5 MB). Even worse, the memory usage kept increasing the longer I used it (after about 10 minutes it was up to 19 MB already).
It appears to have a more active community than LiberKey. The latest version of LiberKey was updated two years ago, which suggests to me that development is very slow or even stalled (?). Also, I installed AIMP on both platforms and found out that the PAP version was slightly newer than the LiberKey version (build 1332 vs. 1324).
In the end, I uninstalled LiberKey and went back to PAP. For me, the #1 knock against LiberKey is its memory consumption -- 15+ MB of memory for a menu system that is mostly sitting idle is just too much, and on principle I removed LiberKey from my system.
What I don't like about both PAP and LiberKey: when you launch any portable app within their system, a second helper process is always loaded at the same time and sits there until you close the app. I understand that this is necessary to maintain the app's portability, but it's still kind of annoying. That's why I only install a PAP app if there's no other way to make it portable. For example, does TreePad Lite really need to be part of the PAP platform? I've been using a portable version of it for years, so have no need to install it through PAP. The same applies to The Guide; a recent update added an option to make it truly portable, so I enabled this option and uninstalled the copy in PAP.
One of the main benefits of installing all portable apps through PAP used to be so that you can quickly search for an app to launch it, but ever since Windows 7 you can pretty much do the same thing using the standard Start menu (you just need to add a shortcut). The other main benefit of using a portable app suite is to keep all the portable apps updated. However, the app update mechanism in PAP isn't very robust (and there's still no auto-update), so this benefit is larger than it seems. If you are against portable app suites, then you may consider downloading all your portable apps through FileHippo.com and using their Update Checker utility.
