Your piece makes a lot of sense. One thing that NFI does do (that NLY doesn't do) is it is hedged and this compensates for the GAAP shortfall. Taxble income is the metric that is used for dividends and GAP does not take in account the hedge factor. Both are violatile PPS--subject to short attacks and both have done well over several years in spite of the short attacks. If you have the stomach for the ups and downs of PPS and want to keep on collecting dividends, history has been good--of course there is always the caveat that history doesn't predict future returns.
Nothing guaranteed, especially when you are asking for double digit divy's--but both of these Reits with their different customer bases have treated me well. Utilizing a DRIP and putting as much as possible in tax defered IRA's makes them even better. I am long on both.