It depends on who you listen to. Bullet proof is also a term used for Muncie 4 speed transmissions. They were installed in GM HD trucks for 50 years, numerous military vehicles, HD forklifts, common choice for off road specialty vehicles, and others.
Nothing wrong with Warner transmissions however.
Fred

1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine