To be honest, I didn't notice that much of a speedup myself, other than Quadrant. Not sure how much it makes a difference, at least it's very easily removable. I must have installed/uninstalled ~12 times today.
From my reading of the European Galaxy S dev forums, there's a (hacked) firmware fix for this for good. I do notice very real lag when other applications are doing something, writing, processing, etc.. it doesn't happen too often, but it does seem to hang, so I think we have some of the lag problem still there that needs to be addressed. We'll see what happens in Europe first, but it's looking promising.
Yeah I was reading about that too, I also noticed that it hadn't been done on the vibrant successfully yet though so it may take a while.
As for the lag, we wont notice it as much but it does help out when your loading something that has alot of data such as facebook twitter and other stuff like that. Oh and btw I did not write the .bat file but Alex said I could modify it if I needed to so yeah we could add some logic in there to ask but as many people are having problems doing a simple root. I dont plan on confusing anyone else lol.