Hah...the same old debate..Rana sahab let them come to the Civil Service,CST's and the CSA,then they would see for themselves which group is better..Jub kursiyon ko taala lgana pare twww.. :p
p.s: Never ever make the mistake of preferring IRS over Customs.Customs has a bigger role than only revenue collection.They protect the nation's borders against illegal trade,smuggling,false migration/immigration and human trafficking..They are going to have additional powers in these regards soon..
and I guess CSP's know better about their trade than those who haven't entered the service yet.May God grant you success so you can see the facts yourself.