I have these two Wahl Clippers : All in One Stainless 9818 & 9639

I had read that you could zero gap the Wahl balding 5 stars clippers, but as you said some people had injured themselves, since they act like a ER surgical cuts you'd get with feather or med prep DE blades and such.

I really like my OneBlade from Philips, but the blades don't last 4 months since I use them on my head, and more like 4 weeks or so. That's why I was thinking to get a foil shaver. BBS isn't really important to me on my head as long as I can trim it low like I do when I use the OneBlade and shave ATG.

I looked a bit more online and found these reviews by Rum Barber interesting on YouTube:

The Best Barber Foil Shaver? Babyliss Pro Foil FX 02 Review: https://www.youtube.com/watch?v=DVQr_5pgIn0

Best Barber Foil Shaver 2019:https://www.youtube.com/watch?v=vwrSeqbYNiE