Joe Strazzere's remark is spot on. There's no standard way for factoring in pension benefits because people have different values. Basically, your decision is an investment one, and probably stands better chance of being discussed ad nauseam at Money SE
The risks are:
- age-specific risks of your death/death of spouse,
- unexpected changes in your lifestyle and consumption pattern,
- significant downturns in the economy,
- outright pension fraud,
- defaults on securities in the portfolio,
- regulatory changes (tax, prudential supervision),
- large exchange rate swings,
- probably a score of other factors I have inadvertently left out.
There are objective formulae to calculate the value of various alternatives, but unfortunately they don't reflect the fact that human judgment is less than rational. With this in mind, though, I recommend that you spend at least some time catching up on investment decision making and asset pricing. It may be a bit difficult on first and even on umpteenth readings, but your future well-being is at stake - forewarned is forearmed, they say.
P.S. In no way can this post be construed as personal investment advice. If in doubt, contact a professional advisor, do not trust random people on the Internet.