Most of my assumptions, at least historically, are pretty conservative and based on slightly pessimistic assumptions. I'd much rather be surprised on the upside than the downside. Assuming health care inflation of 8% per year going forward (a WAG to be sure, and depends on a lot of factors), my spreadsheet tells me I can probably make it by around age 49 to 52.

Have you though of buying healthcare stocks as a hedge against rising health care costs? If legislation brings down health care costs for prescriptions for example, these stocks will suffer. If the political climate favors them, healthcare costs will rise along with these stocks? If you have some 10% of your port in healthcare it may serve as a hedge and reduce your volatility relative to healthcare costs- one of your major outlays.

It depends on what you want to achieve as well with your expectations. I am thinking it might not be so bad to work on contract jobs on occasion- if finances demanded- for semiretirement earlier than full retirement.

It is interesting because I am contemplating seriously what to do with around 20k in cash- sink it into the mortgage for guaranteed return, or drop it in the market? I think it really comes down to what I want- a higher risk with a potential earlier retirement, or a more secure future with a lower cash flow requirement? I am not sure what I want, but I don't like the overall overvalued market.