The reality is that, if you visit any large recording studio, you won't find Alesis monitors at the mixing desk. Normally you will find full range speakers. Our local studio uses high end Genelec monitors with a pair of 15" subwoofers for monitoring mixes. If you were to mix using bookshelf speakers as monitors the end result would be overly bassy. A lot of engineers prefer to mix with headphones for that matter.
The Alesis bookshelves are good, accurate speakers but they are bookshelf size and limited for that reason. They are huge sellers with amateur recordists. I think they are also a pretty choice for home audio as long as they are coupled with a subwoofer. But to compare them to the B&W 802's (one the best speakers I've ever owned,) for example, would be a losing proposition.
As a veteran of years of bias controlled listening tests, I can tell you that any two different speakers I've ever tested have show an audible difference. In fact we've had some matched pairs that showed audible differences between the two identical speakers. There are a lot things in home audio that don't show audible differences in bias controlled listening tests but speakers aren't one of them. That's test results, not opinion.