Well, it really depends on what factors you are considering. Would you have a particular use for the lump sum that you could not achieve using a drawdown arrangement e.g. pay off mortgage and save on the interest? Do you anticipate UK income tax going up in the future such that you think accessing money earlier will reduce total/future tax liability, or a related legislative change? Would you do something with the lump sum to invest/use it such that returns would be higher than leaving it in the SIPP investment for longer? Is your objective to maximize total money available over your retired life, or to favour more money when younger (and perhaps more active so spending more or needing more until state pension kicks in), or to favour more money when older (to cover possible care/health costs etc.)?