I am invested in KMR and love the unit dividends. I have been selling KMR units when I have a capital loss, thereby never paying any tax on dividends if I was invested in KMP. For me it works. Eventually will sell all my KMR position which is not in the near future, at which time I will sell some passive investment property with a huge capital loss.
KMR units can be used as a good investment tool if someone has a diversified portfolio of investments, meaning just not stocks.
KMR pays in additional shares--it's a DRIP. KMP pays cash which is treated as "return of capital" for tax purposes. Just reduces your cost basis when you sell. No tax liability until then and long-term cap-gain at that point.
KMR is not a DRIP. It is a payment-in-kind dividend system. In a true company sponsored DRIP you are getting paid a dividend, which you are then automatically using to buy new shares (i.e., reinvesting dividends). A DRIP has several tax consequences; you get allocated cash (a taxable event) and then you purchase more shares (increasing your invested tax basis).
In the KMR PIK dividend no cash ever changes hands; the IRS views it as a mini-split. Your total basis is unchanged, but is now spread over more shares.