Ya ya, I have travelled in 1A August kranti also, it is fine, you will get similar quality and service, though not sure whether you will get the blue birth ones or red berth ones. Only problem will be too may stops, and Nizamuddin station is a small station with only 7 platforms, it gets too congested with lot of local passengers sitting and crowding on platforms as well. New delhi station is one of the major and busiest stations in delhi with about 20 platforms. The 12951/12952 train takes lesser time and few halts. Almost same quality as both are rake sharing and similar onboard staff too.