Sy,
A whole lot of the stuff you read involves backtesting, or what one famous poster wrote about in a memorable piece called "Predicting the Past." His name was Ozark, and he was a retired American Airlines pilot, and he was smart and sassy.
Frankly, I take a whole lot of the financial theory mumbo-jumbo with a large grain of salt (actualy, a shot of single malt scotch) because the very people who argue that you can't forecast returns seem quite willing to forecast expected future returns, which is kind of like the extended forecast at the weather channel
Take slice and dice as an example. How deep should an investor drill according to theory? Should you just have domestic and international equity + nominal bonds + tips? Or should you go after sub-asset classes--small, mid, large (both domestic/international), add a dollop of REIT (domestic and foreign?), throw in more international bonds (sovereign and corporate), how 'bout a bit of junk, or commodities, value tilt etc. etc. etc? Sheez. Maybe there's a secret grip that's required.
I think Bogle is definitely right that a sensible investor seeks the market return, and capturing the basic asset classes (without drilling to the middle of the earth) at the lowest possible cost is the way to go. Rick Ferri started a nice thread a while ago at Bogleheads about the core four, and I know you are familiar with Scott Burns's work.
Interestingly, what gets lost in the conversation is the utility of life-cycle planning--establishing your minimum (if not more) standard of living in the safest investments possible and seeking to establish consumption-smoothing throughout your investment lifetime (both in accumulation and decumulation).
Bobcat, at Bogleheads, has done a wonderful job of calling attention to the excellent economic work of Zvi Bodie, Larry Kotlikoff, and folks like Poterba, Milevsky, Munnell, and even some of the more recent Ibbotson research that shows how exclusive reliance on safe withdrawal rates can lead to a heckuva bumpy financial existence.
The volatility (or lack thereof) that matters most to me is that I know from month to month and even year to year what my income will be (that much I can forecast), because I do not rely on portfolio income for either fixed or discretionary expenses. Annuity income, including Social Security, offers a terrific method of consumption-smoothing. Obviously, devising ways of making such income inflation-adjusted is a significant, but not impossible, challenge.
Like Ray, I too run a legacy portfolio, but it's subject to RMD when the time comes. So while my intentions are good the taxes won't be terribly pleasant.
Here endeth Bob's epistle for the day (actually for the week). Off to Dallas. Cheerio. Bob U.