So here are my experiences with Helium:
I'm quite happy - thanks to evidemment who saved me after hours of frustration. Once you know, that you have to uncheck ALL USB-options, though, it turns out to be quite a good alternative to Titanium.
I managed to transfer about 150 apps from my FP1 (no Helium-activation via PC required - just grant SuperUser rights... ah... the good old days) to FP2 (activation via PC required after every boot) - wich saved me a lot of re-installing from the Play store.
I didn't need the payed version as I transfered all my data via my SD card. So, no cloud access needed. And it's probably also faster when you want to transfer complete apps and not only app data.
As to which app data transfer really worked and wich didn't I'll find out in the coming weeks. SMS for instance just worked fine (you have to grant Helium SMS rights when restoring). Also the save data in my niece's favourite games made it to the FP2. My favourite Netflix-search-app "iStreamGuide" didn't manage to transfer my personal watchlist, though - but that might not have worked with Titanium either.
Some apps can't be transferred with Helium at all - but Helium does list those apps as not backup-able when you use it on your old phone. So, take a good look at that list an maybe write down somewhere which apps you have to re-install seperately.
WhatsApp for instance allows you to do a complete backup on the old phone and then simply transfer this folder to the FP2 BEFORE you re-install WhatsApp on your FP2. All your chats will then be restored during the re-installation process.
To transfer my contacts I used two methods: First I did a file export directly from the contacts list onto my SD card and then imported this file on my FP2. But I also did a backup an restore with MyPhoneExplorer. The reason I did both is: MPE also saves Facebook or WhatsApp contacts, which Android doesn't - but Android on the other hand does save custom contact categories (like in my office I have "Boss", Secretary", "IT-Support" and so on), which get lost via MPE.
I also backed up and transferred my calendar via MyPhoneExplorer because I don't want Google to synchronize every step of mine.
So, to sum things up, I'm quite happy with what Helium achieved. Still, though, lots of things to do until my FP2 looks and works like I want it to...
(Oh, and is it just me or does the touchscreen become incredibly jumpy once a few apps are running simultanously?)