The NM Hwy 9 route from Rodeo to El Paso is more direct and faster -
but it is really remote and somewhat bleak.
Columbus has services, but the funky store at Hachita is hit or miss.
I would use caution with stealth camping on this stretch -
because of the border immigration issues and, especially, coyotes (people smugglers).
If time is a factor, then Hwy 9 will save a couple of days.
For many people, Hwy 152 over Emory Pass between Silver City and Hillsboro
is the high point of the trip - literally highest elevation - and beautiful.
But there is a good deal of climbing and it can be chilly.
People doing the ST in winter often encounter snow, but spring should be clear.
In fact, spring is the driest season in the Southwest with lots of blue skies.
And trees, and little forest service campgrounds nestled by the creek.
Silver City is a mid-sized town with all services.
Hostel, bike shop, small college, funky cafes and music venues.
But it is also small enough that it is easy to bike around.
Hillsboro is like a time machine back to the 1960s.
Plus, the ride down the Rio Grande Valley is lovely.
Las Cruces is much bigger than Silver City - largest city in southern NM.
Just south of Las Cruces is Mesilla - you have to visit the plaza & historic church.
Mesilla is a lovely place to have a meal at an outdoor cafe and enjoy April weather.
I'm very fortunate that my sister lives in Placitas and my best friend in Silver City.
It's been a wonderful break from Wyoming winters for 30 years.