OMG, so tired of reading comments from people who don't understand how annuities (which is what CPP is) operate. 

Yes, you could change CPP to give you back all the money they've collected from you plus whatever interest. However, your payout would be lower since the payout factors in people who don't live all that long. 

So would that be better or worse? 

As for having an RRSP instead of CPP, most stuff I've read shows that the CPP gets good returns and has very low admin fees. The average Joe-Blow wouldn't be able to do as well investing in his RRSP.