What's the difference, though? I'm genuinely curious.
I would think that oil sands would be more corrosive - or at least more abrasive. I'd think that an accident would be more likely, though I wouldn't hazard a guess as to the absolute likelihood. Refined gas might have a lower hazard rate, but potentially bigger hazard?
I'd be inclined to let market forces work and let the oil companies decide. By which I mean that any expenses occurred by federal, state, and local agencies, as well as individual citizens, would be passed on the owner/user of the pipeline - with zero burden to taxpayers. That would give the owner of the pipeline a pretty good incentive to accurately weigh risks of refinery siting, as well as plotting the specific course of the pipeline.