I usually carry my prescription mask, regulator, housing and camera in a small Samsonite with wheels. Both my wife and I have similar bags and have been using them for years.
Yesterday my wife flew from Ft Lauderdale to Puerto Rico on Spirit.
They had to turn over to an attendand every piece of carry on luggage that had wheels. No exceptions. They were all taken to the belly of the plane.
She had to take some things out of the bag and put then in her purse.
Not sure if all airlnes will be doing the same but a warning for all of us that carry all our sensitive and delicate equipment with us.
I guess they figure that if it needs wheels it is to heavy or big to store in the overhead compartment (although it has been done for years) and a way to get you to pay the $25 per checked bag something I would not be offended to pay if I had 99.4% certainty that my luggage will arrive intact at its correct destination.