MTM vs TM ... advantages/disadvantages ?

By MTM I mean two midrange sized speakers , one at the top and one at the bottom of the cabinet and a tweeter in the middle . Where as the TM would have a tweeter at the top and the mid at the bottom of the cabinet .
I would like to know what the differences , in sound , are between these two designs . Does one design lend itself to a particular type of use over the other . I am refering to standmount/monitor style speakers .

Thank you .