I had a good final salary pension when I retired, enough to live on. I also had ISAs comprised of self selected eqities and Investment Trusts. Although the pension has not risen as fast as the cost of living meaning that pension income has fallen relatively, I have kept my ISAs and ridden the market up and down since 2000. In spite of the turmoil during this period - LTCM, Dot Com and the present bust - I have more than kept my original capital intact. You just have to hold your nerve in bad times.

Bruce is of course right: if you have no time, talent or interest to look after and monitor the progress of investments, then keeping money in an occupational pension will be better, especially if you think you will never need or want to access the capital.
But doing so is not risk-free. The risk is that CPI lags even further behind the rate of inflation on the goods and services you need / want in retirement.
Dennis: CPI has lagged RPI in most years in the last decade, and I expect the margin to be maintained in the immediate future, because RPI, unlike CPI, includes housing costs. Even if house prices fall, mortgage and maintenance costs are likely only to rise - present ultra-low mortgage rates cannot be sustained for long. Given the differences will be compounded over, say, 20 years, the difference in year 20 may very well exceed 20%.
Even RPI is likely to understate the rate of inflation of prices for the retired, especially if they need any kind of paid-for care or personal assistance, or any other service with a high labour content (ask Age Concern about that).
I should confess that the background to this is that I am convinced by the 'global shift' story, with the East becoming relatively (much) richer over the next 20 years. And I don't entirely buy the 'great global UK companies' story, so I am investing mainly in the far east and emerging markets.
OK, I can afford to take the risks involved (not that I think they are huge) because my residual pension (the bit I can't cash up) and state pension will for the foreseeable future give me more than enough to live on. But I want to be as free as possible to relocate abroad if / when health / family concerns make that desirable. So tax-free cash in stocks and ISAs is better for my purposes than taxable pension income.
As to worries about what that will return, the past cannot be a reliable guide to the future, but as a very passive ISA investor over the past 14 years, I have averaged well over 7%+CPI despite a few poor calls along the way. Investing more actively this year, I have done better still. If you need a steady income year on year, mine is not the path to choose, but if you can afford to ride out the squalls and cope with an average over time, I don't think 7% + CPI is too hard to achieve.

Agreed - and there is great variation between schemes - £12 for £1 in LGPS, and £17.5 for £1 in the other scheme I know well.
Clearly taking cash out of the latter is more attractive than from the former.
The spouse's pension, however, is not affected by the decision on taking cash in either case - it pays the same on death of the contributor no matter what cash was taken.
Surely no-one who is even thinking of buying an annuity in the UK should even be thinking of maximising the tax-free cash from a DB pension.