You are best to do a search on RBW since there is a wealth of info and opinons there about QC's.
I may have been wrong about omni parts for BC's and dry suit inflators, I may be confused with CJEN ( I think CJEN is like the scubapro AIR 2 QC).
Things to consider in QC's for rebreather use
compatability with other gear and or divers
Amount of water immersion if connected under water. ( very bad for CMF valves!!)
QC's seal both ends when disconnected (Double End Shut Off or DESO vs Single End Shut Off)
Swagelok wins on all accounts except compatability. This may be an issue on BIG dives with other RB divers but its not a concern for me at the mo or any time soon.
Omni swivel use check vavles on the male QC. These will stop gas escaping from the QC but it the external pressure is higher than the internal pressure water will get in! For this to happen though your gas lines would have to be empty which isnt all that likely unless you entered the water with no gas turned on or pre charged.
All QC's will allow a small amount of water immersion when connected under water. Swageloks will probably allow the least while I think Omni will allow more due to the lack of DESO and the internal space of the male QC before the check valve. Dont connect the gas line in the water and there is no issue.
I am told dive gear express sell omni swivel. Let me know if you are going to order them since I also need some gear from there.