Okay, so I generally have an idea of who typically gets targeted by the Harvesters:

1) Eldritch and Elder Casters are the primary targets as they have the 'spark' within them to manipulate the Arcanum.

2) Divine Casters would hold little-to-no interest with the Harvesters, as their power is based entirely on faith and rote-memorization of established formulae.

3) Primal Casters would similarly have little interest among the Harvesters (from my read) owing to the fact that they are conduits of another being's power rather than (necessarily) being actually independently able to manipulate the Arcanum without intervention.

4) Psionics are. . . well, we have indication that they CAN be targeted by Harvesters, and there is even a Finger dedicated to it (the Handless Society), but overall they are not high priority targets for Ymandrakes.

5) Sorcerer-Priests of Sarish are. . . complicated? They are that middle ground between Divine and Eldritch casting, which means they probably hold some interest for the Harvesters though by no means a priority target.

6) "Interesting" cases of magical creatures of phenomena, such as magically cursed beings, biotechnology creations, etc.

My real question here is such: We know that the Harvesters are not particularly interested in hunting Psionics, but they DO like interesting magical creatures, would the Scions of Ven val'Sosi be priority targets among the Ymandrakes? Now that there are a few players who actively play these people, should they be more circumscript about the use of their powers in public lest they be targeted?

I am pretty sure the answer will eventually be yes. Ymandragore would love to experiment on the brood of Ven. Worse, the Brood of Ven are physically unique so hiding isn't an easy option for them. On the other hand Ymandragore is playing a long game and I don't think there are currently any research projects that really need a "Brood of Ven" to keep pushing what can be done with the arcanum.

The Harvesters & wizards in Ymandragore pay a lot of attention to who's style of magic is up or down, but I don't think these things matter in the big picture. I think the best way to think about the Harvesters would be to equate them with procurers in a mystical "Manhattan Project." Mostly the Harvesters grab new recruits and or "batteries" but If you need 5 pounds of unobtainium to complete important research then someone (the harvesters) are going to get that too.

As we all know the SK wants to be a True God (capitol G) and is juicing up on the mojo of the arcanum in his bid to get there. As such *ANYTHING* that touches on the arcanum is potentially "interesting" as a source of inspiration or experimentation. It's all about further the understanding and exploitation of the arcanum. As a result you can expect the odd Kio to be abducted to look at the heritage of the High Kio and/or their connection to the elements. You can expect the odd divine caster to be kidnapped to study how the faith component of their tradition works ... and perhaps to try to find a work around so that the effect of Cants can be used like sorcery. You can expect anything weird and magical to be tinkered with. Eventually.

As an aside it is my IC and OOC opinion that eldritch and elder Traditions of manipulation are only favored is because (1) most people can learn them and as a result (2) most of the "research staff" use those Traditions. The other traditions present problems. But if things were different then I believe the other traditions would be the SK's primary focus.

In the D20 days Harvesters did capture magical beasts and mythical creatures for the purpose of experimenting on them and syphoning magical energy from them. In the Year of Ill Harvest you come across a menagerie in a Harvester base with described having nonspecific creatures and a dark naga held in it.
It makes sense that the Handless Society would try and capture the Brood of Ven to see if they could create psionics in humans, or the Denaki dwarves.
Or simply recruit them into the Finger to get a foot hold in the Black Talon society.
I'm sure the other Fingers try and capture Black Talon arcane casters for the same purpose.

One point about your list Cody. Number 5 Sorcerer Priests of Sarish. Henry has said that Ymandrakes consider them to be divine casters and they should have no fear of capture just like any other divine spell caster. I wish I could find a link to where he said it. But he was very clear in his statement, SPS are not hunted by Ymandrakes.

val Holyrn makes a good point. A Harvester would capture whatever they think they need to further themselves, their Finger or the SK's goal. So in truth no one is 100% safe from Harvesters.