I have to finish it off by giving the Haimu whisper credit where credit is due. The holes in the bottom housing + the relief cut give off the perfect "quiet" sound I need at work but also gives me a great, satisfying tactile feel and bottom out that makes me like these switches more the more I use them. I'd recommend you watch the video Maker Mods made for these switches if you made it this far.
(I am writing this because there is no way to edit my original review)
Looking at the price of my boba u4t and seeing how much the boba u4 is, I would recommend people who can spend a little more to just get the u4 instead. You are getting a lot better build quality.
For the Haimu whisper switch, there is no pretravel, but the actuation point is basically at the bottom-out point. Coming from my boba u4t at work I used to type gently, and with the Haimu it sometimes would not register my key press.
They are definitely quieter than non-silent tactiles. And the bottom out isn't mushy since there is no rubber. But the travel is very scratchy and unfortunately, lubing can't really fix it. The factory lube is best described as disgusting. If you want to properly lube these switches you will have to clean off everything. Especially on the feet of the stem and the leaf. It will gunk up otherwise. The plastics are some of the worst quality I've seen. The switch basically fell apart after trying to take it out of the plate for the first time. The bottom housing was stuck. The clips were basically ripped off. The plastic is very bendy and there is a lot of housing wobble and stem wobble. The upper stem to stick on keycaps is also way looser. I feel a lot less confident the keys would stay on the board in a worst-case scenario. But overall, if you can get these switches at their listed price without having to pay crazy shipping fees or duties, they could be worth it. I have grown used to them after using them for a bit and I like them enough that I don't want to replace them in my board unless I need to.