plop,
i switched from a 750ti to a 1660ti 6GO OC a few weeks ago, Linux with “almost fresh” nvidia drivers and a R5 2600.
Am almost a noob to sculping, just tested it a bit after reading that thread Pablo Dobarro's master plan for sculpting and his official sculpting branch
Which i hope you already know.
My test at 38 000 verts was super cool smooth and all.
With today blender fom buildbot, i just took that 38 000 verts mesh, applied a subd 2 and got a 900 000+ verts, it looks smooth to me with basic brush like drawing grab pinch.
1 Subd later, at 3.7 millions it’s totally unusable.
Applying subd ate my system ram (16 go) to 90%.
With a build a week far, a 900 000 verts mesh was also a terrible experience.
Improvements to sculpting mode are actually fast, but can’t tell much about any bottleneck along the road of sculpt mod usability.
So far, the 1660 was a good catch for other projects to benefit from eevee especially, like basic environments, 1 millions verts, with multiple basic instanced meshes collections re-instanced 
300 000 verts vehicles,
volumetrics
basic animations
and all
are just perfect and smooth, a real joy to work with 
With all sculpting and overall performance improvements incoming it’s really a bless, but i can’t tell for your actual needs you will need some pros around.
Oh i forgot, NO MORE 750ti barrage. No.