I've just bought Lightroom 3 (I'm still with XP and 4 won't run on it). I think the option is there to edit in another application, but only if you want to - 4 may well be the same. I've also ditched Photoshop CS and have bought Elements 10. As far as I know, the trial versions are full versions, and if you want to buy, you can purchase a key online, but I found it cheaper to shop around. I got 3 from PC World (online) for £99.
I've certainly edited and printed from LR without going via Elements. It took a bit of time to get my head round that fact that, in LR, you don't edit and then save the file, but so far, I'm really pleased with both programmes.
I looked at Elements several times on Amazon, then had an email from them, offering a lower price, which was handy.