Since trying my first balanced tension set 6-8 months ago I have been in love with the idea. Where the option exists, I will never be going back to a regular set of strings. 
 
Why are they great? 
Very similar tension across all strings makes chording and consistent playing a breeze. Of course it is possible with a 'regular set', but it is simply easier like this. 
As per usual, D'addario strings sound great and easily last a month of regular, heavy playing (or two if you don't play too much). 
the 11-50 set is perfect for my d-Standard guitar (and you could exchange the 50 for a 56 if you wanted drop-c with a balanced tension - I have tried it). This particular guitar has the 25.5" scale. 
 
Negatives? 
What negatives? 
I can't really think of any, however I don't gig often so I will add a notice that D'Addario also make strings which they claim last longer. If you end up very sweaty during a performance, these strings might not last as long as they do for me.