2.5 or 3 way; why one over the other?

The implementation is far more important than 2, 2.5, or 3. 

+1 @wcfeil.   

Well said and the bottom line truth of the matter.  

The electronic  and philosophy  is different 

tatyana gets my question.  I appreciate all the info on the technical differences between 2, 2.5 and 3 way systems but I live far away from any place to audition speakers, let alone ones from several different manufacturers; so, when I see (in print) the description of any particular company's  speaker systems in the same series (price point) and they have both a 2.5 and an 3 way, otherwise similar in size (may vary an inch or two in height) and construction, and a few dollars difference in price, what should I expect as a difference in sound between the two. In your collective experiences, why would one tend to prefer one over the other?   A typical example is the Dynaudio Excite X34 and X36. 

Read and digest the info on those 2 dynaudio speaker. Read reviews of each and comparisons. Speak to the dealer. Tell us what you learn and what “specific” questions you are left with.