I've found it a bit like "what car did you drive in to work with today" in that any typical current and working car is not going to be a stark difference to a high end car in terms of how fast you get there... but you'd definitely notice a piece of crap with a donut, broken heating, and screeching brakes causing you problems if that's what you were comparing instead.

I.e. I can count the number of times I said "wow, uBO Lite didn't make this site usable but loading up Firefox with uBO and it worked fine" on one hand. At the same time, if I ever look and compare how much is actually getting blocked, uBO is definitely blocking way more. Doing a side by side compare of dozens of sites it becomes easier to see minor differences I wouldn't otherwise have noted, but may not have mattered as much.