It seems almost without exception, that every Warlock I see is using Supremacy, either with the Observer or Wrathguard; very rarely I'll see a Warlock with a Felguard. Now obviously it's what sims out very marginally best on a Patchwerk encounter, I get that, but I'd have thought that with all the encounters this tier with temporary damage buffs, or downtime between phase changes that there's a lot of opportunities here to get a bit more out of Service to overcome that tiny margin. Afterall, the extra pet can be stacked with those damage buffs, and it's cooldown keeps on ticking while your Supremacy pet is forced to stop DPSing. Let's take a look at the encounters:
Jin'rok - Puddles.
Horridon - Stacking vulnerability debuff
Council - Target switching can lead to some downtime, but also a lot of guilds do this by zerging Sul making Service the obvious choice
Magaera - Head switching leads to downtime
Ji'kun - Puddles
Primordious - Mutated buff
Iron Qon - Lots of phase change downtime
Lei Shen - Lots of phase change downtime
So on 8 out of 12 fights, there's pretty decent potential to be able to get a bit more out of Service, so how come people aren't using it? I'd also question the use of the Observer, as it's actually the pet most susceptible to loss through movement/switching due to the short range on Tongue Lash, but that's a slightly different thing...