The fourth driver relating to in the event of death. With the NHS pension if you were to die only 50% of the pension income is left for your wife. When your wife passes, zero is left for your family. As appose to with a QROPS 100% is left for your wife and then 100% for your family as a legacy:

The fith driver is relating to income tax. The NHS pension is taxed at source. If for example, if sometime in future you were to move to a location world wide that has zero income tax (i,e Dubai/UAE), you would still be taxed at UK rates in the UK. In contrast, a QROPS income is paid gross and if you are living in a tax free location, the income is not exposed to tax. If you were to move back to the UK to retire, only 90% of a QROPS income would be taxable as HMRC identify it as a European Penson Scheme.