I wouldn't be so sure of that. They blocked my Smart Card once. All channels were showing black screen error, even though my base pack and addon packs were active. After I registered a complaint with Customer Care, a local technician called me and asked me if I used my STB with a different Smart Card (or my Smart Card in a different STB). I told them no. Then they told me to email them photos of my Set Top Box in such a way that the Serial Number on the box's label was visible. When I inquired why, they told me that Sun Direct usually disables/blocks Smard Cards/STBs of users who try to use them with a different STB/Smart Card. Then they unblocked my channels after verifying the photos I emailed them.
So, even though I am not sure if they can identify if we are using this hidden menu, I believe they could still block all channels for any given Smart Card, if they want to. I mean, isn't that what Smart Cards are for -- to block all channels after the base pack expires?
Note:
A month or 2 before this happened, I actually did try to use my Chennai Smart Card in the Sun Direct STB we have in Salem. I wanted to see if it works, so that I could use that method to view TV whenever I went to Salem. Because we did not recharge the Salem Smart Card regularly. Well, it did not work. I guess because Sun Direct somehow ties each Smart Card with a particular STB, in such a way that only those 2 work together. So, from then on, I have been taking both my Chennai STB and Chennai Smart Card to Salem. I just plugin the wire from my Salem Sun Direct's dish antenna to my Chennai STB, and it works fine.