By way of additional comment, it's important to recognize that the base CPP is a modified pay-as-you-go plan, and that's in contradistinction to the additional CPP, which will be a fully funded plan.
As for a pay-as-you-go plan, we're a relatively young investment organization with contributions still exceeding benefits payable, so arguably the risk tolerance of it is higher than a standard pension fund, and that's why we're taking the decision to up the risk equivalent nature of our investments over the next few years.
The additional CPP is a fully funded plan, and as Mark pointed out in his opening remarks, that implies a heavier reliance upon investment income, both now and in the future, and this will mean that the additional CPP will have to be invested with a lower risk tolerance than the existing fund.