I am strongly against a level cap for entry to the instances. I intend to rank up all my DoW & DoM to 50 over time, and I don't want to be punished for this by being excluded from participating in newly introduced content.

Does anyone care that R50's can kill the mid range NM's to get the gear for their other classes? Not at all. Maybe it was annoying for some in the first week when the NM's were camped, but after that it make no difference at all. It is no different with instances. Infact it matters even less as I don't expect they same conditions will apply with camping. The beauty of instances is that how other people complete an instance is of no relevance to anyone other than the people who complete the instance in that manner.