Quad Hets...but it depends on if you think the Extreme gene is a just a Hypo gene taken to the "extreme" or if it's really something different, like a T Amel (type1).
I think that many of the "Falcon Extremes" out there are T Amels...and some are more than likely Hypos as well (or het Hypo)...making them T Hybinos (type1)...I say this based strictly on my interpretation of what I've seen...nothing else.
I also think that Terry’s Mega gene is more than likely a T Amel (type2), hence the type1 delineation above.
Then when you throw in the Hypo term for reduced amount of black then that's another discussion all together…because you have reduced intensity(shade of gray)...and reduced pattern...which I feel are two very different types of Hypos.
I personally thing the Hypo gene needs to be broken down into some more "detailed" or distinct groups...I don't know, maybe others have already done this...
I know long explanation...but if the Extreme you used has been bread to a "normal" hypo and all hypos were produced...then I would consider it a T Hybino type1 het Anery(AKA Falcon Extreme)...therefore all your "normals" would be considered het for:
T Amel (Falcon)
Hypo (reduced amount of black intensity)
Anery (standard)
Amel (standard)
&
Hypo (reduced amount of black pattern)
Quad hets that are het vanishing pattern.
-Rusty