Xantcha et retour sous contrôle ambigu

[15:12] <Bringer4> Hi! What happens if in a 3-player game (let's call me A, and my opponents B and C), B has resolved !Gather Specimens this turn and I cast !Xantcha, Sleeper Agent? Do I get to choose whether gather specimens' or xantcha's replacement effect applies first, or does gather specimens always take priority?
I was convinced of the former but the gatherer ruling about what happens to xantcha when a player lose the game (she isn't exiled and goes back to its owner) surprises me. Would that also mean that if I also control a !Suture Priest, I'll get 1hp rather than have her final controller lose 1hp?
[15:12] <Fryatog> Bringer4: Xantcha, Sleeper Agent {1}{B}{R} · Legendary Creature — Minion · 5/5 · As Xantcha, Sleeper Agent enters the battlefield, an opponent of your choice gains control of it. Xantcha attacks each combat if able and can't attack its owner or planeswalkers its owner controls. {3}: Xantcha's controller loses 2 life and you draw a card. Any player may activate this ability. · [...]
[15:12] <Fryatog> PZ2-R,C18-R · Vin,Leg
[15:12] <Fryatog> Bringer4: Gather Specimens {3}{U}{U}{U} · Instant · If a creature would enter the battlefield under an opponent's control this turn, it enters the battlefield under your control instead. · ALA-R · Vin,Leg,Mod
[15:13] <Fryatog> Bringer4: Suture Priest {1}{W} · Creature — Cleric · 1/1 · Whenever another creature enters the battlefield under your control, you may gain 1 life. Whenever a creature enters the battlefield under an opponent's control, you may have that player lose 1 life. · NPH-C · Vin,Leg,Mod
[15:17] <Popetoper> you choose which replacement effect to apply first
[15:18] <Popetoper> the xantcha didn't enter under your control so the opponent loses life, you don't gain
[15:19] <Bringer4> But then, say that I choose to apply hers first, give it to B (preventing the other from applying so gather specimen is out of the equation now) and B loses, shouldn't she be exiled in those conditions? The gatherer says otherwise, why is that?
[15:19] <Bringer4> (xantcha's gatherer link: http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=450651 it's the sixth ruling)
[15:19] <Popetoper> yeah, I know the ruling
[15:19] <Popetoper> I am not entirely sure why they ruled it that way
[15:21] <Bringer4> Someone suggested that perhaps, xantcha did enter under her owner's control but that she would change sides during the process (before any player gets priority, of course) would that be possible?
[15:21] <WizardMN> Xantcha has a control change effect; when Player B dies, the control effect giving them control of Xantach wears off. Since the default controller is the person who tried to put her onto the battlefield, it goes back to them.
[15:23] <Bringer4> But that wouldn't apply to gather specimens, right? Are you implying that Xantcha still enters the opponent control, but was somehow worded so that it creates a continuous effect giving control rather than merely entering under someone else's control?
[15:25] <WizardMN> Yes, that is exactly what happens. A CE exists granting another player control of Xantcha. Notice the difference in Xantcha's wording compared to Captive Audience
[15:27] <Bringer4> Ok, thanks! Just to be sure, what Popetoper is still correct? both gather specimens and xantcha's effects would apply in 616.1b as they would change under whose control xantcha would enter (albeit in different ways) so you still get to decide which applies first?
[15:27] <WizardMN> Also, I am not sure that you actually get to choose the order the replacement effects apply. Since Xantcha's effect *doesn't* modify under whose control it would enter (it enters under the owner's control and then they choose someone to gain control of it) I think you need to choose Gather Specimens first.
[15:28] <Bringer4> ah!
[15:28] <WizardMN> It is kind of tricky. I can see where they both apply in 616.1b, but, again, the wording it slightly different so I can see it going either way
[15:29] <Popetoper> they apply at the same time though because they both change whose control it enters under
[15:29] <DoubleFried> Xantcha is a >:( of a card
[15:31] <Bringer4> Yeah, it's kinda awkward, I guess I'll just frown very hard upon anyone playing gather specimens in response to xantcha and default to "both apply in 616.1b" for now. Thanks a lot, and sorry for monopolizing the chat for that much time!