If I'm not mistaken, Vince was helping fund ecw and in return taking a few wrestlers here and there. So there was no way for them to become THE promotion. I loved ecw but it was more of a niche company at the time anyway.
That's always been a myth that Heyman shot down on his documentary.
The deal was that Vince wanted Too Cold Scorpio. Not a problem, except Heyman was getting money from Tommy Boy Records by promoting one of their groups, who did Scorpio's entrance music. Heyman didn't want to lose out on that money, so Vince offered to pay the company whatever Tommy Boy was paying them, as well as send wrestlers in return for guys like Scorpio & Funk. Wasn't no extra money, ECW was getting the same from the day they began using Scorpio, except from a different party.
On topic, it's hard to say because ECW wasn't as well known, during the "glory days". So, by the time it went national, everything that made it stand out was done.
As far as Raven's Nest, for example, being admired on a certain level, it was an imitation of what was done in the territories but, IMO, was well received enough to the point that both WCW & TNA ran the same angle back a few years later. Wasn't admired on a DX or nWo level because it wasn't as popular or known to the wrestling public but appreciated and respected enough that it gave Raven something to do in other companies. Definitely on a higher level than Aces & 8s.
If anything, ECW was more ROHish. I say that because of the emphasis on young, fresh talent, with an inclusion of a few name talents that helped build it up. Look back at the early days of ECW, with Don Muraco, Tito Santana and Ivan Koloff, to name a few. Compare that to ROH, with Abdullah The Butcher, Dusty Rhodes and Terry Funk. It was never about them but always about the "newer" guys.