Wait a minute, so only after cessation of material existence can one have the ultimate realization i.e unity with brahman, but we need material existence to share our experience with the ignorants, is this experience / realisation temporal ? I read on wikipedia that Nir-vikalpa is point of no return & you have said RamaKrishna Paramhansa returned from Nir-vikalpa, may be R.P. never reached that level, so it was possible for him to return, may be it was his ego playing tricks on him. The same can be said for Buddha.
hope you will bear with me.