Depends on the situation. Like I said, I think rubber would be fine over on the passenger side, but where they cross the engine and run down within inches of the manifold is cause for concern. The thing is, heat transferred by thermal/infrared radiation is proportional to the exposed area (percentage of field of view to be specific), to the temperature difference, and to the emissivity of the surface. The exhaust is really effing hot so it's radiating a lot and and black rubber will absorb almost all of it (emissivity 0.95) while shiny aluminum absorbs almost none of it (emissivity 0.05). That means the foam under the aluminum is unlikely to ever exceed the temperature of the surrounding air, while any rubber that can "see" an exhaust manifold runner or precat could easily reach way hotter than the air (think of a blacktop surface in direct sunlight). It could definitely make a 40° difference but I'm not sure either option would stay below their rated temperature. The safe bet would be to just not insulate the last few inches going to the compressor at all, but rig up a heat shield. It might not even be a bad idea to shield the discharge line from picking up exhaust heat, even though in general you don't want to insulate that line since it acts as condenser surface rejecting heat.
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That emissivity factor I described earlier is somewhat a factor of color but it's also about the surface finish. Just because those lines are aluminum doesn't make them equivalent to foil- the unpolished matte surface probably bumps their emissivity to 0.7 or worse.
