Kamar akar jaye gi.. Once I traveled from KHI to RWP in Daewoo and I didn't like the experience. Plus Sindh has worst roads now a days (because of maintenance) with lots of diversions which will be a bumpy ride. Daewoo choose Kabirwala, Jhang, Pindi Bhattian, M2 route which is also not in very good shape.
Bus is OK for short journeys but I never prefer it for long routes. In train you can eat, sleep, walk without any problem.
Choice is yours.. save a few hours, travel by bus OR more comfort, a few hours more.