This would also be a good source for information on 'structure' asked earlier by andevenabs, who was correct is saying MLPs like SXL are more like REITs than Royalty trusts when in comes to capital draw down.
1) there is a 15% canadian tax on their royalty trust distributions even in an IRA so a US trust is a better IRA bet.2) Taxes deferred are still taxes sometime, barring stepped up basis from death,and I personally would put a US trust in an IRA. 3) UBIT tax is definately a problem and a pain. I did not think all mlp's generated UBI, it arises out of debt financing. 4) your advice on the primer is good.