I think the largest hurdle in having a meaningful discussion about Social Security is the age old conceit that it is somehow a separate entity, distinct from the federal government. Income taxes and SS taxes have been linked for decades. When SS collected too much, the rest of the government spent the excess. Now that SS costs more, funds from income tax are needed to balance the ledger.
It would be more productive to decide how we will tax people as one topic, and decide what programs we want as a separate topic. Once we know what we want, then we just need to make the numbers match.
Americans clearly need a pension plan. We have taken on all the personal responsibility we can handle by switching company pensions to 401k's. We need something to rely on that Big Brother manages and takes the risk for if there is a shortfall. It would be great if this were a true pension fund, but I see 20 years of heartache, bankruptcy, and early death getting from the current pay-as-you-go system to a pension fund. Both systems would need to be funded during the 30 ish year startup, so I think we are stuck with the current system. We could fiddle with payouts somewhat, but since so many people rely on this as their primary source of money, adjustments have to be minor.
On the tax front, we need to sum up all taxes and make them work together for the system to be as fair as possible. Property taxes are regressive, so federal income taxes need to be progressive to compensate. We should have a VAT, since economists say this distorts the economy less. We also need to link regular income tax and payroll taxes into a combined number. Looking at only one of these creates huge misunderstandings of who is paying in. (hint: almost every worker pays at least 10%, even after EITC). Stop counting retirees as workers in the stats. Last, the rich should pay more, probably 30% net at least. They have a lot more assets to protects, and the military and our financial structures do that for them.