I don't know about that, maybe from a skill set perspective, but Nedomansky's highs seem higher than Petrov's. Nedomansky was selected best forward at the 1974 World Championships; Petrov was never selected WC Best forward. (4-3 advantage in WC All-Stars for Petrov, though Nedomansky's WC career was cut short by his defection). Nedomansky was almost certainly the 2nd best forward in the 1972 Olympics behind arguably the best performance of Kharlamov's career; did Petrov have an Olympics that strong?
Points-wise, probably not. The 1976 Olympics were arguably Petrov's best; he was 7th in scoring, and in the deciding game vs. Czechoslovakia, he scored a goal (which he also set up with K & M)* and assisted on the GWG, when he won the faceoff in the offensive zone and fed the puck to Kharlamov**.
*
http://www.youtube.com/watch?v=YrMss9voDv4&t=61m5s
**
http://www.youtube.com/watch?v=YrMss9voDv4&t=94m11s
Maybe it's just me, but I'm not overly concerned about the Olympics pre-1998, though. Quality-wise, IMO they weren't really any better than the WCs, for example. I'm sure that the players themselves wanted to do well in them, since it WAS & IS a special event & held only every four years, but sometimes they seem a little overvalued. Also, Czechoslovakia finished only 3rd in 1972... and 5th in 1980, even though many Czechoslovak players were among the top scorers... how much glory there really was? (compare with Holger Maitinger & Ernst Höfner at the 1981 WC)
Anyway, in the early 1970s international tournaments, Nedomansky was arguably better than Petrov. Then again, he is 3 years older than Petrov, and Petrov's best years and many of his best tournaments were still ahead of him (1975 & 1979 WCs, for example).
In the mid-1960s, Nedo also had a reputation for being a 'choker' in big games; i.e. against USSR. But I guess the 1969 WC changed that, and he was always a key player from that point on.
Basically, I think there are reasons to prefer Petrov (you listed them above). But there are also reasons to prefer Nedomansky, IMO.
Nedomansky was a helluva goal-scorer - along with Firsov, probably the best in Europe in the late-1960s/early 1970s. But Petrov wasn't too much behind (e.g. over 50 goals a season in the Soviet league), and he seems to have been clearly more defensive-minded and arguably was able to use his teammates better (compare their assist numbers, for example).
Of Czechoslovak players, IMO Nedomansky's international record is on par with Martinec's - and clearly better than Novy's, whose international highs are fairly high (1976 CC, 1976 WC, 1977 WC & 1980 OG) but who doesn't have much to show beyond that (internationally).
But I certainly know a lot more about e.g. Petrov (and have seen him play a lot more) than about Nedomansky, so that is a problem here.