Yeah, I think that VB4 in particular looked to bulky, and was just downright unappealing. I like the way that XenForo is moving, as oppose to vBulletin.
As for editing posts, you just scroll over your post, and you should see "Edit". But more likely, I haven't got all the correct permissions set up at the moment.
It's not possible (realistic) to run both softwares. I think that you just have to get used to it, especially to benefit from all of the features. As for the shoutbox, we have one - it's at the top, and say "Shoutbox"; click it.
I love it, it's clean, simple, sleek, awesome, cool and stuff and words. I love it and yay for no more annoying you ro make DevBest run on xenForo. Go me!
It was, when I look back on a Vbulletin forum I feel pleased we moved. I've actually got use to some of the features I've found out some the moderation sides and all in all it's a great forum software to use. It offers loads of ways to socialise you get the shout box along with conversations. I personally like the status feeds myself.