It's worth adding here that Lightroom has the best of both worlds in this respect. The radial mask, and the grad mask of course, is editable at any time - which is critically important in my view - and yet you can still paint additions or subtractions to it. This makes masking very powerful in my view.
Capture One, also has this feature, in fact Capture One's ND mask was editable before LRs almost 2 years or so. The Radial mask has always been editable, and has the same basic flow/opacity controls as LR's.
I agree on the Macbook pro 15", the brush icon as it you slide it towards the smaller sizes, just disappears, thus use of smaller brushes is hard at times. Not the case for me on windows machines.
Not sure about the Luminance masks point, as C1 has a highlight/shadow adjustment slider, IMO basically the same as LR's. And this can be used in a local adjustment.
I do a lot of brush work also in C1, don't find a problem with painting broad areas, with a fine edge brush, as the controls of the actual brush make that pretty easy for me. Again similar to LR's at least to me.
Auto Mask, in C1 could easily be improved, as it is only really accurate on true solid edges, like a building. Unlike LR's auto mask, which many times can make a very accurate selection around a tree line.
Of course, LR still won't allow you to turn on or off an individual adjustment brush as you can a local adjustment layer in C1. You can delete an individual adjustment brush and see the effect and then use the LR history (which I greatly wish C had) to bring it back, but I prefer C1's ability to to just uncheck, or re-check an layer.
LR allows duplication of a individual brush, as does C1, but C1 also has the ability to create a layer from a previous layer (thus a duplicate) and then invert it. Not sure LR can do this at least I can't figure that out.
Paul C
Black/White adjustments, best done in C1 in the curves tool, or levels tools (old fashion tools similar to CC), I would like to see a black/slider in C1 also.
Hotkeys, don't use them, but I am sure that if you are a user of hotkeys, it would be a nice addition.