The old meters do not have this two tariff system.Until and unless they replace all meters or most of them, they will not start this two tariff regime.If total load of house is upto 5000Watts or 5kW, then according to IESCO website they charge you as per old rate slabs and if its above 5000Watts then they charge you as per Two Tariff regime.So they are charging single phase meter customers as per the older slabs and only single phase meters are I think considered upto or below 5kW.
And only 3 phase meter customers are poor souls who are being charged as per Two tariff regime and there must be some 3 phase customers who have installed 3 Phase meters but there total load does not exceed 5kW but they are still being charged as per Two Tariff regime.And IESCO or LESCO or any DISCO dont care whether a person's house load is above or below 5kW(as they dont check while changing meter or installing new meter) but wherever 3 phase meter is installed, they will charge Two tariff regime irrespective of load....What a system they have evolved to mint money....So those who consider there load is below 5kW......change to single phase.......but after reconfirmation with your respective power supply company....as things always change in Pakistan.
As per my experience of digital meter they are not fast.At my home in Kohat, our analogue 3 phase meters were changed to digital ones(not Two tariff regime one's rather simple ones).Both the meters are fine in my opinion as we have compared previous year's same months consumption of old meters with new ones and thats almost the same.But they do have faulty meters which must be FAST.and one of my uncle's home single phase analogue home meter was replaced with digital one and thats very FAST....faulty....
And lastly while checking the readings, if Serial No.5 and 6 dont show up and you have to wait longer.Repeatedly press the upper button again and again until you get reset screen and then date screen.....then wait for the serial numbers 5 and 6 they will show up to you after sometime.
And these meters also show many different things like voltage etc and load in kV at particular time and many other things.