Salam Tanvir,
As already said the capacity reduces to half of the capacity available.
As far use in urban areas is considered I think this is not a gud idea as the intersite is very less and havin asite with this much of power will disturd the frequecy plan.
So its better to use this feature in rural areas and HW.
One more this I like to add we can use it in OL/UL mode.
Hope it will help.
Regards
Tufail