I would never advocate anyone doing something they are not comfortable with, and OP I think you have clearly made the right decision, but I am totally amazed at the hysterical nature of this thread in terms of some of the responses.
People are saying things like even if there was a 1 in 100,000,000 chance why take the risk. Well most people get in a car every day and there is sure as hell a much greater risk than that, that you would be killed. People take measured risks every day.
I have been known to leave my DDs in a hotel room, it was a small hotel (10 rooms) that DH's family had hired out the whole of for a family party, we used a monitor and it was fine. On the night of the party we kept the DDs up till 9:30, they went to bed and I then sat with SIL on a sofa in one of the communal areas near the stairs drinking some wine and chatting for another hour or so (with a monitor). On another occassion in a different hotel, we had a family room and it was in an annexe not attached to the hotel itself, so we got a babysitter and she sat in the room while the DDs slept in the bunk room off our room, we also ran a monitor between the room next door where SIL's baby daughter was sleeping and the babysitter listened for her and checked every 15 mins. Again all was fine, the babysitter was from an agency and CRB checked.
I personally would not use a listening service and I would always consider whether to leave the DDs on a case by case basis and would only do it if I really felt comfotable.
But examples such as, they could choke, get up and pull something on top of them etc ect all these things could happen in your own home. My DDs have blocked up a bathroom sink while I have been oblivious downstairs. Do you all run monitors at night to listen to every breath and noise while your DCs are asleep one or two floors about you? Would you use a holiday club facility and leave your DCs there where you couldn't see them..?
Anyway as I said I think you have made the right decision for you OP but I think there is a lot of scare mongering on this thread and I think in the right situation this could be perfectly acceptable.