Lubuntu vs Ubuntu 12.04

I have an HP Mini 110 netbook (I'm rocking 1GB of RAM) and I'm itching to upgrade from Ubuntu 10.4 to 12.4, but now that I'm all set to do it, I'm wondering whether I would be better of switching to Lubuntu instead. If I were to do so, I would remove some of the included applications and replace them (installing Firefox, Thunderbird and VLC for exapmle). I know there's the whole gnome/unity debate, but I'm willing to give unity a try and see how well I get used to it, so that's not much of a factor for me. What I'm interested in is: would there be much of a difference in speed/energy use/hard disk space between the two if I were customizing each with my preferred applications anyway?