Folks,
1.3Vso is the one getting really close.
After Garmin, there are only a handful of GPS receiver chip manufactureres, (12 channel) Rockwell is probably the most common. They will be found in handhelds, panel mounts TSOd or otherwise for IFR, boats, cars, you name it.
It is the circuit board design that the GPS receiver chip/module/engine/wotever is attached to, which is where it all really happens, with RAIM capability close to the top of the list in importance, if it is to be IFR certified.
The RAIM handling by the C146/146 systems, compared to C129/129A is significantly different, and the change is much to be desired. If you are looking for a TSOd GPS for an aircraft, don't even thing about C-129, unless it is only feeding and IRS/FMCS.
Handhelds are great devices for VFR navigation ---- but that's all, folks!!
Tootle pip!!