If you make the choice, it is binding for the tax year you make it and for any later year that you are a real estate professional. This is true even if you aren’t a real estate professional in any intervening year. (For that year, the exception for real estate professionals won’t apply in determining whether your activity is subject to the passive activity rules.)

In most cases, all rental real estate activities (except those of certain real estate professionals, discussed later) are passive activities. For this purpose, a rental activity is an activity from which you receive income mainly for the use of tangible property, rather than for services. For a discussion of activities that aren’t considered rental activities, see Rental Activities in Pub. 925.
Ali Boone(G+) left her corporate job as an Aeronautical Engineer to work full-time in Real Estate Investing. She began as an investor in 2011 and managed to buy 5 properties in her first 18 months using only creative financing methods. Her focus is on rental properties, specifically turnkey rental properties, and has also invested out of the country in Nicaragua.
One of the things I'm surprised your article doesn't mention is the tax advantages of this type of investment. The depreciation and rehab costs (purchasing distressed properties) can be huge deductions to ones income taxes, which none of the others have. Then, along with the appreciation of real estate, this passive income investment outperforms the notion of maxing out my 401k as well.

In the case of an activity with respect to which any deductions or credits are disallowed for a taxable year (the loss activity), the disallowed deductions are allocated among your activities for the next tax year in a manner that reasonably reflects the extent to which each activity continues the loss activity. The disallowed deductions or credits allocated to an activity under the preceding sentence are treated as deductions or credits from the activity for the next tax year. For more information, see Regulations section 1.469-1(f)(4).
I just wanted to say how nice it is to see such a positive exchange between strangers on the Internet. Seriously, not only was this article (list) motivating and well-drafted, the tiny little community of readers truly were a pleasant crescendo I found to be the cause of an inward smile. Thank you, everyone, and good luck to you all with your passive income efforts!! 🙂