>>14118942It does matter or you will have to justify through magic why the incline makes any difference at all compared to ninety degree free fall where they would both travel at the same speed.
The easy way to identify this by looking at rotational energy in either bottle. The liquid bottle will use less rotational energy if the fluid is weakly coupled to the rotating internal surface of the bottle, but this coupling is dependent on the forces acting on the water which are directly related to gravity(ramp slope) and rotational speed(compounding rotation acceleration, ramp distance). As others have already mentioned, the rotation on the liquid is likely to be less perfect than the rotation of the solid so if the rotational energies are equal then there will be more losses on the liquid bottle, but you really have to be sure that the rotational energies are equal.
Suppose you have two cylindrical oxygen tanks and one is at half of the pressure of the other, which one rolls down a ramp faster?