The Seeker's Arrow is a very interesting Rite I think. You look at it and think it's a Rite for bikes but it doesn't actually require any bikes at all, so you can end up with something really quite different to the Skyhunter Phalanx or the Ravenwing Protocol. Of course it lets you take a lot of bikes in it if you want, but it doesn't make you do so. (Incidentally, this is one reason I feel it's wrong to argue that Book 9 means that the Ravenwing Protocol is superceded - the Seeker's Arrow is really very different to the Ravenwing Protocol and seems to be reflecting a different aspect of the First Legion's way of war).
Ideas like the above, mixing the different Scions and coming up with unusual combos are where some of the potential is found I think, in the Seeker's Arrow and some of the other Rites. Although whether any of the combos are actually worth the points is a different question! I do think that the Scions push you in the direction of larger units, so the Scion tax is spread over big units and you don't have to buy the upgrades as many times.
When I was looking at ideas for the Seeker's Arrow I thought I'd have one six man unit of jetbikes as compulsory troops, and fill the other slot with a large unit of infantry, probably assault marines, who'd get more benefit from Scion of the Ravenwing, and then a large unit of plasma repeater Outriders also with Scion of the Ravenwing (so they can outflank on a 2+).
HQ is interesting. One idea is to have a Praetor on Jetbike - feels thematic - with Scion of the Ravenwing and hit and run, and possibly a command squad. Expensive though! Effectively you're paying 45 points to get hit and run and add 2" to your charge distance. Obviously this guy would have a combi grenade launcher with stasis shells. Alternatively you could have him footslog. Could stick him with some Tartaros terminators for example.
I'm not sure how to use the one measly Heavy Support slot. I feel a Sicaran is asking for trouble. Likely to face the entirety of the enemy's anti tank, and die quickly. A Fire Raptor could be a good choice of course, but means you need to look to Fast Attack for serious anti tank - so I guess Javelins, Speeders, Sabres, Xiphons and Primaris-Lightnings. Oddly, I think the Seeker's Arrow does allow Rapiers. Not sure how I feel about that, but again it's a good example of how this Rite isn't just about building a bike and jetbike army (assuming I am reading the limitations correctly!).