Some things have to be made clear (I have the PX4d and the Toneport).
1. The presets on EVERY Multieffect are useless. You never get away without tweaking, because equipment is different.
2. The Pandora and the Toneport are two completely different things.
3. The Pandora PX4D is good and you can get awesome sounds out of it. It is a very nice opportunity to practice stuff whereever you are because of the integrated metronome and drum patterns. You can jam with it everywhere because you can record some seconds over a drum/bass track.
4. The Toneport is an audiointerface, that's why you can't really compare it to the PX4D (you could compare it to the PX5 though). The UX-2 (169 EUR I think) has two line ins AND 2 mic ins.
It IS an external soundcard with integrated mic preamps. You can record with a mic, the UX-2 is able to record a dry track without all the effects of Gearbox (the program in your PC). So you can use it instead of your current soundcard (just turn this one off).
So you see that you can't compare both things, but you CAN compare the PX4D to the Gearbox Software.
This software delivers the same basic tones like the POD which I like very much. Of course you can - just like a POD user - download the updates like Metal Shop for awesomeness (I don't have it, but I heard it). Plus, you can download and upload other User Tones, they can be sorted by the name of the guitarist or the band.
I prefer the sounds of the gearbox, but for practicing and playing guitar at your girlfriend's place with headphones, the PX4D is unbeatable.
I'm not so experienced in tweaking the gearbox settings, but it's basic presets amaze me more than the pandora's.
My conclusion: If you want to record stuff, take the Toneport UX-2 because you won't need another soundcard and because it's able to record dry tracks. What I forgot to mention is that you can buy the Gearbox software as a VST too. That means: sounds can be switched afterwards.
If you want to practice and if you are focused on mitch's tone (like 99% of the users here, no offence) AND if you just like the tones of the Pandora very much, take the Pandora.
By the way, my friends of Begging For Incest recorded their latest demo with the sounds of the POD Metal Shop. I think it ran through an ENGL poweramp, but you can get an idea of the possible basic tone.
Listen to "Awaiting the Fist" (and consider that it was a recording studio):
http://profile.myspace.com/index.cfm?fuseaction=user.viewprofile&friendid=154108786