"From the posts in this thread an observation one might make is that it was Hamish McInnes and his Terro that made the biggest impression on modern ice and mixed climbing."
Here is a second answer to the same question. Hopefully the picture will be more definative.
In effect not a lot has changed from the original Terrodactyls. The handles and picks have gotten longer and more ergonomic but past that...really not much. Slight improvements on the Terro...not all that impressive when you look at the actual lineage. Biggest advantage is the additional clearence that has been with each new generation.
As a comparison Black Diamond offers 4 technical tools. All with about a 2 degree change in pick angle between each of the 4 tools. About 10 degrees over all last I heard. (Reactor, Viper, Cobra Fusion) No where near that much differeence between the originals Terros, the Chacal and the Nomic.
Anyone that originally climbed hard with a Terrordactyl could very easily switch to a current Nomic and climb much, much harder with a lot less effort. And.....more security. If you liked a Terro, a new Ergo would make you think it true bliss by comparison. At some point the newest tools just becomes cheating :) But even the Ergo is just a Terro with more clearence than a Nomic.