Metal sintered and oil impregnated bushings tend to have higher friction than polymer bushings and potentially higher wear on the shaft since these likely aren't hardened. That and their lubricant can run out, whereas the polymer bushings keep lubricating as long as the bushing is there, they just get sloppier in terms of their tolerances.
Honestly I think either will work, one is less maintenance (polymer) one has more constant tolerances over time (metal).