I'd rate the R2D2 much lower than 5%, at least as far as your conscious experience goes. Your brain might technically be kept in a vault or canister somewhere, but there would be extremely good virtual reality linkups to the brain. Look how good movies are getting with current VR. They have to simulate physics and human anatomy in considerable detail, but often take shortcuts to make the characters cuter and sexier. This is much more likely to be what you have to look forward to. Weirder than you're used to, but much more appealing than you are thinking here. And that's all just talking about a possible non-uploaded existence as a meat-brain. If you were to be uploaded, the possibility of being limited in your communication to your environment is even lower.
Even if you were stuck in an R2D2 body or something for years on end with no high-end virtual reality, it is doubtful that you would experience boredom or depression. Boredom and depression is an emotional state with particular neurological characteristics. These can be disrupted (even now) by drugs. Furthermore, it seems likely that boredom is dependent on hormonal and/or electrical responses from the rest of the body. A brain by itself probably could not feel boredom without significant prosthetic assistance.
The very notion of existing as a brain in a can means we've solved the problem of figuring out how to synthesize and deliver every chemical and stimulus the brain depends on. The delivery mechanism would be digitally regulated, and thus we could feel excitement, boredom, or any other emotion on demand -- perhaps even copying these sensations from healthy volunteers. That may not be an optimal human existence, but as an in-between state while waiting on life support to be restored to more optimal humanity it does not seem likely to be unbearable.
For a pop-culture example, take the Cybermen from Dr. Who. (Ridiculous show with ridiculous premises, just using it to make a point.) Their emotions are turned off, but only because their bodies are total pieces of junk that can't support a brain with emotions. However we've seen that the emotions of the brain can in principle be turned back on again. Thus if you were to take away their tendency to be fanatical killing machines and replace it with something else (fanatical lab equipment manufacturers, say), since they can't feel pain it wouldn't be a bad thing to be a Cyberman for a few years while waiting to be transplanted into a non-stupid body.
I could wake up in the matrix... I don't know if I'd want that. Even if it was designed to make me happy. I want meaning, this requires having access to reality. I'll think about it.
drugs
Why would I want to do that? That is even worse. I am disgusted by the idea of having no ability to do anything of use, and even more disgusted by the idea that the solution to this situation is to drug me so that I can't properly care about the problem. If I'm not able to interact with reality, what is the point in existing?
...it wouldn't be a bad thing to be a C
I heard that women are difficult to convince when it comes to signing up for cryo. In mentioning cryonics to a dying person, there seems to be a consensus that it's not going to happen. I encountered a post: Years saved: Cryonics vs VillageReach, which addressed my main objection (that the amount of money spent on cryo may be better spent on saving starving children, especially considering that you could save multiple children for that amount of money with high probability whereas you save only one life with low probability by paying for cryo). Now I'm open to being persuaded.
My first instinct was to go read a lot about cryo, but it dawned on me that there are a lot of people here who will want to convince family members, some of them female, to sign up - and these people may appreciate the opportunity to practice on somebody. It has been argued that "Brilliant and creative minds have explored the argument territory quite thoroughly." but if we already know all of the objections and have working rebuttals for each, why is it still thought of as extra difficult to get through to women? If there were a solution to this, it would not be seen as difficult. There must be something that pro-cryo people need for persuading women that they either haven't figured out or aren't good enough at yet.
So, I decided to offer myself for experiments in attempting to convince a woman to sign up for cryo and took a poll in an open thread to see whether there was interest. I don't claim to be perfectly representative of the female population, but I assume that I will have at least some objections in common with them and that persuading me would still be good practice for anyone planning to convince family members in the future. Having a study on persuading women would be more scientific but how do you come up with hypotheses to test for such a study if you have no actual experience persuading women?
So, here is your opportunity to try whatever methods of persuasion you feel like with no guilt, explore my full list of objections without worrying about it being socially awkward, (I will even share cached religious thoughts, as annoyed as I am that I still have them.), and I will document as many of my impressions and objections as I can before I forget them.
I am putting each objection / impression into a new comment for organization. Also, I have decided to avoid reading anything further on cryo, until/unless it is suggested by one of my persuaders.
Well, have fun getting inside my head.