For the record the management company rules are legally binding and you signed up to them when you bought your house - any rules introduced by Petra on behalf of the management company are binding (provided they were approved by the management company and not just Petra themselves who are the managing agent - not the management company). It is unfortunately not as simple as saying 'it's my house i can do what i like' when you have literally signed a document to the contrary.
We were told about the Sky Dish in the management company rules document - however my opinion on that is that it is superceded by Cairn wiring the houses for sky and advertising the ability to get sky in the sales particulars and when i spoke to Cairn at the time they actually advised us where to put the sky dish so as not to void the warranty on the house and said she didn't know why Petra were advising no sky dishes. (we didn't end up going with sky as they were useless).
With regard to the ring door bell or CCTV none of that was in my contract so i can't comment however we'll soon be installing both so we'll soon find out!
It is highly unlikely that Petra on behalf of the OMC will clamp down on the sky dishes - if you are genuinely concerned raise it in advance of the next AGM and ask for a vote that sky dishes be allowed.
Hope this helps!
PS i've been i shackleton crescent for 2 years - it's a class place to live a and quiet street we've had no problems - you will always get a seat on the bus as you're the first stop (that may change with the new bus connects and the proposed route from adamstown station). The traffic is bad but nothing worse than other areas outside of the M50 - if i leave the house at 6.45 i can be in clonnskeagh for 7.30 - i left this morning at 7.10 and was at my desk for 8.20.