The paper demonstrates the ability of ASPECT v2.2.0 to reproduce the benchmark by Zhong et al 2008 and therefore its ability to handle varying viscosity in a natural convection scenario within a 3D spherical shell. The authors prove that by comparing vital benchmarking parameters like Nusselt number, v_rms and temperatures, along with profile plots of steady-state solutions. 

A few remarks:

- Although equation 5 states this, it is usually important to point out that the Rayleigh number is defined with the viscosity at T=0.5

- Please cite  http://dx.doi.org/10.1016/j.pepi.2013.04.002 as we did a similar study with the CITCOM benchmark. 

A comment: The usability of ASPECT for 3D spherical shells seems questionable as you write in 3.1 that the case A8/9 (viscosity contrasts of 10^6 and 10^7) would have required excessive computing resources. Given that this is a benchmark from 2008 and computers got a bit faster nowadays, it seems there is an issue. If this is not the main use-case of the code this is fine, but people need to be aware of that in order to not waste computing resources and help the environment. 

This manuscript is a solid contribution, demonstrating the validity of ASPECT at low to moderate Rayleigh number when compared against the CitcomS model.  I only have a few questions/comments to add to the previous review.

Some time is spent comparing and discussing different stabilization techniques but did the authors find that stabilization was actually necessary at these low Rayleigh numbers?

Since one of the response to a previous review mentioned that it might be, would it be possible to include a demonstration of ASPECT at more extreme viscosity contrasts/Rayleigh number even if a comparison to CitcomS isn't possible?  This could prove useful for future code comparisons using this paper as a benchmark.

Rather than just comparing the '%diff' in top and bottom Nusselt numbers in the results tables could some quantitative comparisons be made between the codes to clearly demonstrate their similarity.

A few minor comments:

 - line 27: presumably the length-scale is D not D^3

 - line 9: the Rayleigh number alone doesn't describe the problem as it also depends on the choice of boundary conditions, which are given later but perhaps this sentence could be rephrased to "The Rayleigh number (plus apropriate boundary conditions) can describe this problem..."?

 - line 21: only equations (1-3) are solved, not (1-4), which includes the definition of Ra

 - equation 5/table 2: it would be a convenience to those trying to reproduce this to provide the values of E used in table 2 rather than just the viscosity differences

 - equation 10: assuming Omega is the volume of the domain (is this defined somewhere?) it seems unusual that the definition of RMS velocity uses the square root of Omega, is this a typo?

 - line 23: "This allowed isolate" -> "This allowed us to isolate"?  This paragraph feels a bit repetetive of the previous paragraph, which also discusses the use of uniformly-spaced meshes in the radial direction.

- line 27: the doi given for Bangerth et al. (2020b) only appears to go up to Figure 123, could you please check this reference to Figure 130?

 - line 23: please clarify the phrase "ASPECT is very likely converging with higher mesh resolution for this parameter as well"

 - table 1: units for gravitational acceleration are incorrect

 - tables 5-10: incorrect quotation mark used around '% diff' in all captions