I found a statemamt that thre are very few mods that were made with possible 1.6.4/1.7.2 transition(without loss or corruption of world) What are they?
Eh, that depends on the mod. If it doesn't add any world features or anything that has changed from 1.6.4 to 1.7.2, the mod will most likely work.
Still, most mods work on updating from one version to another.
Still, most mods work on updating from one version to another.