Slaughter 24s were actually better than the 72s sometimes, IMO. I think that was because the map was actually super concentrated (all nodes spawned on the top part and there were no big nodes, meaning you had to jockey for position more), melee were more effective than BLM-stacking there, and healers were target numero uno a lot of the time so I always had to watch out for dogpile into melee LB. In Shatter ice still spawns all over the place so it's hugely annoying and just means you spend a lot of time running around PVEing things instead of killing people.
I like objective-based modes, but Shatter could do with the only ice spawns being the ones in mid for 24-man.