The OH-58 is primarily a MK1 Eyeball scout; UAVs and the Apache w/ MTADS has largely replaced the old school. It isn't necessarily better or worse, just different. Except, the sensors don't have to get close to things, so they have reduced risk.
As to the X-2 concept, the upper limit of scalability is a very closely held Sikorsky secret, but from what I've inferred from industry types the S-97 is easy. Something significantly bigger than a Blackhawk gets troublesome.