I did the same today and have the exact box, which I believe is an HS3C02.
In my experience, I am not noticing much of an improvement in picture quality, but audio quality is positively better. I came from Tata Sky+ box with DVR. In that regard, I am struggling with pausing/ rewinding live TV on Airtel DTH.
I have connected a 16GB USB drive. First off, I received a message that it is not one of recommended drives. Now, where do I find that list?
Second, on Tata Sky I could just rewind live tv anytime. There were settings for review buffer, etc. On Airtel, I realise I cannot rewind live tv. I can pause it, I cannot rewind it. Once paused, when I play, I can then rewind back to only the moment I paused it - so, there is no buffer.
Instant rewind was a feature I loved in Tata Sky, is this not possible in this box?