I'm also using Dish TV HD STB. As we all know, the HD channels quality is superb on Dish TV.
As per my understanding, Dish TV was having only 10 malayalam channels on mpeg4. The rest malayalam channels (apprx 17 channels) were still in mpeg2. But for the last 2 days, I have noticed the PQ of all malayalam channels has improved (sorry, I normally watch only malayalam channels and HD channels). I haven't received any software update on my DishTru HD box.
Is there any option to check whether a specific channel is using mpeg4 or mpeg2?
Also, it is good news that Dish TV is also migrating all channels to mpeg4 in January.