I guess this is more of an opinion gauge than any form of theory crafting, trying to possibly see it from the another side from my own.
I run with a 10man group, who after the pro-longed absence of a raid-member, has been running with a hunter being the only one to provide the group's haste buff. Trouble is for most fights he's also the one providing us with the crit buff or bloodlust; and we can't have all three. Most of the time we end up with haste (depending on who shows up and who doesn't), but there are times where we end up going all night with crit instead. And even when we do get the haste buff, we do not get it during Bloodlust and for the time period it takes for pets to be switched back and forth (if he even bothers to switch back to the haste pet after Bloodlusting).
TL;DR Long story short our group is very unpredictable about whether or not we will get the 5% haste buff covered or not. I'm currently geared for the 6637 haste threshold after several simcraft runs; yielding the highest possible dps assuming full raid buffs. Obviously my dps spikes a little lower when I don't have the buff, but so far (*knock on wood*) never had any issues on dps even when pushing heroic content.
From a min/max standpoint, knowing that the buff pretty single-handed changes what you're stat priorities are. If you weren't sure if you were going to be getting the 5% buff or not, would you even bother attempting thresholds at all?