Years ago there was a prolific poster on ScubaBoard who told of the graduation exercise for an advanced program he had taken--a CESA from 100 feet. I have personally talked to people who have done emergency CESAs from 75 feet and from 100 feet and gotten a full description of the experience from them. Yes, it can be done, and it has been done. Here are some factors to consider.
1. If I were in that situation, I would probably ascend at greater than 60 FPM the whole way. I am not worried about a mild case of DCS. I want to get to the surface. It would take me less than 2 minutes.
2. Once you are ascending and the air in the air in the lungs expands, it starts coming out pretty clearly. It is not like the experience with a horizontal CESA in the pool. The people I talked to said that once it started coming out, it would have been hard to stop.
3. Because of the expanding air, you can exhale all the way to the surface much longer than you can hold your breath.
4. The main reason you can't hold your breath longer is mental. You don't need any more oxygen to hold your breath longer. It's the buildup of CO2 that gives you the panicky urge to breathe. You can get over that. Not only that, the constant exhaling is releasing CO2, so you won't get as much of an urge to breathe as you normally would when holding your breath that long.
5. Yes, as you ascend and the ambient pressure gets lower, you will be able to get air from your tank, and more than you might expect. I tell my students that in a deep OOA situation, your tank is not OOA--it just thinks it is.
If you are in that situation, the worst thing you can do is think you can't make it to the surface with a CESA, because having that bad notion may cause you to hold your breath.