Here's Wade Pfau's overview of the 4% SWR and other withdrawal plans:

"Making Sense Out of Variable Spending Strategies for Retirees"

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2579123 (This link gets you to SSRN's abstract page, and then you can pick your preferred PDF.)

18 pages (large text, big margins) of review & analysis boils down to this 10-item table:

Decision Rule Methods:

[1] & [2] Bengen's Constant Inflation-Adjusted Spending (1994) (the 4% SWR)

[3] Bengen's Fixed-Percentage Withdrawals (2001)

[4] Bengen's Floor-and-Ceiling Withdrawals (2001)

[5] Guyton and Klinger's Decision Rules (2006)

[6] David Zolt's Target Percentage Adjustment (2013)

Actuarial Methods:

[7] & [8] RMD Spending Rules

[9] PMT Formula (ex. Waring and Siegel (2015); Steiner (2014); Bogleheads)

Monte-Carlo PMT Formulas: Frank, Mitchell, and Blanchett Age-Based 3D

Model (2011, 2012a, 2012b); Blanchett, Maciej, and Chen Mortality-Updating

Constant Probability of Failure (2012); David Blanchett's Simple Formula (2013)

[10] Annuitize the Floor & Invest for Discretionary

He concludes:

"Choosing a retirement income strategy is complicated by the fact that there is no single number which can summarize all of the characteristics of the strategy. The failure rate is not sufficient. The tables in this article provide 13 numbers to summarize the performance of a strategy, and all 13 numbers are important. These numbers include the initial spending rate, the evolution of real spending over 30 years at different points in the distribution of outcomes, and the distribution of remaining real wealth after 30 years.

How should a client choose a spending method and parameterize the initial spending rate? This article provides a framework to think about the important issues, such as spending flexibility, feelings about upside spending growth vs. downside spending risks and a minimum spending threshold to be protected, desired direction of spending (for instance, whether to decrease spending over time), the appropriate planning horizon, and any legacy goals.

With decisions made about these issues, clients can decide on an appropriate XYZ formula and then compare the distributions of spending and wealth created by variable spending rules."