I had a 1260 Blizzard and its amazingly fast and compatible. You can't compare it to the 1230IV, I especially noticed stuff like OS3.9 much faster and games like Doom.
But having said that, unless you make a lot of use of that extra power it would not really bother as it is a very expensive upgrade.
I sold mine and got a 1230IV, not because I was not happy with the 1260 but because considering how much money it was worth I was not getting the most out of it.
A 1230IV is great for stuff like using OS3.9, Whdload and even to a lesser degree games like Doom but it does not even come close to the pure power the 1260 gives you.
