Sales have rapid growth in every department, be it banking, multinational or services industry. As far as banking is concerned, Sales representative have rapid growth opportunities as compared to operations staff provided you have guts of marketing and links with business community and have big social circle. You can reach to the seat of branch manager within 4 to 5 years if you do well in sales.
Now coming towards demerits. Sales is a highly risky job. You will be kept on probation for every three months. Meezan bank assigns monthly deposit target of about 4 millions. Besides, you will have to sell different other products of the bank as well.

I' am working as an MTO in a commercial bank. Before that I was offered BDO job in Meezan bank. I signed employment letter but didn't join it later. My advice to you is that think very very deeply before joining any field related to banking.

Regards,