When it comes to the choice of colours, I prefer SteemPro more. SteemX is too dark, and the red ‘X’ I find annoying—if not alarming

Spot on! It is exactly what I had in mind.

First, I have not used either of them. So, I am judging from the pictures that you have shared. The SteemX choice of colours is not the best. It seems that this design would work for a selected number of audience. Unlike, Steemit or SteemPro. I think it can be used on a wider range (since the interface).

Although, I find Steemit itself a user-friendly. So, I think that there should be something else added to these interfaces to attract me to use them. It is nice to have a different choice of interface. To be able to complete with other platforms in that area. We already have the boylikegirlclub interface. But, SteemPro still wins in terms of the design amongst the three of them.