I know what you mean - low TVL slotmask is probably my ideal for most retro systems, but the brightness is just barely not there - HDR1400 should definitely get us the rest of the way there. It’s also possible that the perceived brightness of True Black HDR1000 will be higher than regular HDR1000.
It’s sort of “maybe adequate, takes a lot of work” vs “clearly works” for the ones I’ve recommended.
I haven’t made any attempt to do this since it would mean introducing clipping - I’m probably one or two clicks away from clipping something with my current configurations.
I’m also not using any brightness mitigations - even a single click on some things can yield a pretty significant gain in perceived/actual brightness- after you loosen that restriction, a lot more possibilities open up.
I like RRGGBBX and dotmask configuration about the same, I flip between the two depending on the mood. I think you’re right that the dotmask feels a bit more analogue, but RRGGBBX is quite a bit lower TVL, which has its own benefits - sometimes less is definitely more when it comes to pixel art.
I see you’ve been using a similar dotmask in some of your presets, looks good. As I recall reading, some of the earliest color TVs used a low TVL dotmask (Zenith Chromaclear)- this should probably be paired with a very smeary and blurry composite video signal for authenticity 
Yep, sometimes when you disable these completely it feels a little too perfect, and some things can look a bit better with a bit of fringing/artifacting. Artifacting 0.00 / Fringing 1.00 is probably as good as it gets for a CRT. Sometimes I like to crank things up a bit higher because it just feels right.
Yep, quite a bit - adding the slotmask is a ~25% loss of brightness according to my calculations and confirmed by tests.
I can get dotmask a lot brighter if I use a “standard” configuration- CRT Mask 4.00, Lottes MaskDark 0.00, MaskLight 1.00
This measures 296 nits using the same test settings as my above tests.
Since the RGB triad is 4 pixels wide at the widest point, that’s 540 TVL.
I’m using an alternative dotmask- Mask 10.00, (Transform to) Shadow Mask 1.00
This adds a black pixel, which prevents the red and blue phosphors from blurring together and helps with phosphor shape. Obviously, it’s a bit darker due to the addition of the black pixel.
The TVL is 432, so it’s a bit closer to consumer grade and has a bit more texture.
Taking another look at the Lottes configuration, it’s not that bad if you don’t mind sacrificing the phosphor shape a bit and don’t mind your reds and blues blurring into magenta. The extra brightness is definitely nice. It does need a bit of extra work to fine-tune, though, compared to the others- an HDR adjustment might be enough (needs a bit more contrast)