So why two helicopter types replacing the cancelled Comanche? Mainly because the Comanche, at over $100 million each, was basically another gunship, when what the army needed was more transports (for cargo and troops). The dangerous recon mission was being taken over by UAVs. Rather than spend $14 billion on 120 Comanches, the army preferred to buy some cheaper scout helicopters, and more transports. That led to the purchase of the 368 ARH-70s and 332 UH-145s. Both can be used for scouting, and the army will be experimenting with all sorts of options. Like fitting the larger UH-145s, which will start arriving next year, with sensors. Both the ARH-70 and UH-145 can be armed, but the UH-145 is seen more as a "Blackhawk Lite." The UH-145 is seen as particularly useful for medical evacuation (medevac), where it's smaller size makes it less likely to get hit. Moreover, many medevac missions do not require a chopper as large as the UH-60, so there will be resource savings as well. The first ARG-70s will arrive in two years.
The two new choppers are built using more modern technology, and have already proved successful designs because of several years of use in their civilian versions.
The U.S. Army is rushing to acquire two new types of helicopters. The 2.8 ton ARH-70 (a militarized Bell-407) will most directly replace the elderly OH-58D, while the 3.6 ton UH-145 will supplement both the new ARH-70 and the existing 4.8 ton UH-60 Blackhawk. The 2.7 ton OH-58D was supposed to be replaced by the 5.2 ton RAH-66 Comanche. The cost and weight growth of the Comanche proved fatal. The Comanche was designed at the end of the Cold War, for a kind of war that was never fought, and is unlikely to be fought any time soon.