I've recently received the sliders and I'm sorry to say but I'm a bit disappointed..
Here's what the result looks like
My plan was to mod it with SA Retro but besides the obvious need for drilling, the major problem was the wobble. When a key is released, the cap wobbles like it's attached to a tip of a dildo so I had to go with short profile blanks.
Most importantly, though, is that I had to discard about 20 sliders from my initial installation because the injection mark that's positioned on the cylindrical part of the slider would catch and jam the key halfway.
Here's a demo of the jamming and the loud sound it makes:
After sorting all of the sliders I was able to find the smooth ones but that left about half of all the sliders as rejected
And as an additional sad note, the spacebar I got didn't catch the stabilizer pegs no matter how hard I pressed. This meant that the spacebar would tilt every time it was pressed off-center so I had to go back to the one I got off massdrop a while ago.
In the end I had to hypersphere the good sliders to not be as loud (wobble adds to the volume of the upstroke). The result on the photo is a smooth and working HHKB but I'm just sad that half of the sliders have to be dumped and the limitations the wobble imposes on the choice of caps.