The memory usage has been what chased me off AppRocket every other time I've looked at it - and there have been a few, because it is such an atrractive-looking piece of software. I have used ObjectDock for most of the last year, and been fairly happy with it, but I've noticed over the last few months that I have been using the Quick Launch toolbar more and more, so I switched off ObjectDock a few days ago.
So, right now, AppRocket is running at 14,400k, but F&RR is not far behind at 13,512k - ah, but I just opened and then closed the F&RR window, and wahaaay, it's down to 660k!