I think the TCAP front sight has a Trijicon tritium capsule and is .120 - so perhaps they've figured out a way to get that extra .005 in?
I'm a pretty dedicated Trijicon HD user (I own four sets of HD sights), but recently experimented with the TCAP due to the thin front sight. If Trijicon offered a thinner front sight, I'd be quick to upgrade. I'd welcome a plain rear sight with a wider notch as well.
I wonder if a .125 HD front sight would pair well with the various Warren rears...