two way v. three way speakers


I recently heard some magico mini's at a friend's house. They sounded amazing. And they were 'only' a two way speakers, but they filled the room with amazing sound. So now I wonder, what does the additional driver add, especially when it is the same size as the second driver. For example, the SF Olympica III's have two drivers of the same size. I know that third driver adds a lot to the price, but what does it sonically? Thank you all in advance.
elegal
@McelJO, Yes balance and budget constraints are always a point of compromise in any system, but I was agreeing with you about the use of a quality amp to get better performance from a good pair of speakers.
Add a pair of quality subwoofers to the Magico minis (making sure that they're properly set up and optimized thru the x-over region "the hand-off") and you'll have the answer to your question.
@Maxboy00 - I wasn't intending to imply that we were not in agreement. Sometimes forums, like emails and texting, cause a failure to communicate. We need a more resolving forum, right?
the one ways i just had built beat my old 2 way kestral 2's and my paradigms studio line 2 wys. consider a full range if you really want some drop dead musical presentation. audio nirvana was the brand i got, the 8 in full range classic 8's. i could add a sub but i live in a condo so unlikely and tbh i do not really need it at normal volumes. spend as much as you want on any high quality make or model. i hooked it up to a $300 7 watt tube amp. yes they are very efficient! imo, 2 ways and 3 ways are no0 better or worse than the other..depends on engineering, drivers, crossovers and on and on