The live interaction between the student and the faculty must be there, otherwise the student wont understand many concepts.
The faculty sometimes on observing the student reactions and moods in the class room he will repeat once or twice till he get positive nod from the students
Many people in rural areas cant avail this benifit because of streaming or buffering problem.
and lot more.....................
These are not available in online coaching, By only considering time as advantage my vote to this is Thumbs down.
Sorry it is purely my opinion as i have been taking classes for CA/CWA for last 2 years.