At some point in the future, we hope, brains which have been cryonically preserved may be resurrected, by some process of neural reconstruction (most likely either as nanotech, reconstituted wetware, or virtual simulation).
Imagine that the technology has just come available to resurrect a frozen brain. However, the process has low fidelity, due to resource and technique limitations. Luckily, these limitations are purely practical - as the technique is refined, the process of resurrection will become better and better. The process is also destructive to the original preserved brain, so there's no going back and making a second, higher-quality scan.
The results of the process is effectively a copy of the old brain and personality, but with permanent brain damage in several regions - this manifests effectively as an extreme form of cerebral palsy, partial amnesia (retrograde and anteretrograde), bipolar disthymia, and a partial frontal lobotomy - in short, you'll get something that has recognizable facets of the original, but it's an utter mess.
As the technology progresses, each of these symptoms will be lessened, until eventually they will be effectively eliminated altogether. However, the first few thousand subjects will suffer irrecoverable memory loss and will suffer a horrifically low quality-of-life for at least several decades until the technology improves.
The technology will not progress in refinement without practice, and practice requires actually restoring cryogenically frozen human brains.
Let's establish a metric so we can talk numerically:
0.000 - complete and persistent vegetative state, aka dead (this is our current state of progress in this technology)
0.100 - Terry Schiavo (persistent vegetative state with occasional non-conscious responses)
0.500 - the equivalent of advanced Alzheimer's syndrome; severe mental and physical impairment
0.700 - moderate mental and physical impairment
0.800 - significant reduction in facilities (IQ loss of 20 to 35 points, severe difficulty with memory, slurred speech, frequent and severe mood swings)
0.900 - slight reduction in facilities (IQ loss of 10 to 20 points, moderate short- and long-term memory loss, frequent but moderate mood swings)
0.950 - liminal reduction in facilities (IQ loss of 5 to 10 points; occasional slowness in memory recall, occasional mood swings)
1.000 - a perfect reproduction of your original personality and capability
QUESTION 1: If your brain was frozen, at what stage in this technological refinement process would you like your brain to be revived?
QUESTION 2: If you had had your brain preserved before anyone had asked you this question, how could the reviving technicians ethically know this value? Remember that they cannot thaw you to ask you.
QUESTION 3: Assuming as part of this what-if that the technology cannot progress past 0.500 fidelity without human trials, who should we attempt to revive when the technology is at 0.500? At 0.7? 0.8? 0.9? 0.95? Assume that we haven't asked any of the subjects this question, so we do not know their own preferences.