So, you inspire me (and that I have recently bought a death fields raumjager group to make a tiny stormtrooper grenadier battalion) to describe a DIFFERENT scions list, riffing, I admit, quite heavily off of yours.
Air scions detachment lambda lions battalion
These guys are all
3 tempest prime (my usual warlord/relic, and 3 command rods. One has the laurels of command, and one has the autoreliquary of tibery)
3 command squads of 4 plasma each
2 x 5 man squads of 2 plasma each and 1 plsama pistol
2 x 5 man squads of 2 melta each and 1 plasma pistol
1 x 5 man squads of 2 hotshotvolleygun
1 x 10 man squad of base equipped scions
3 valkyries with hellstrike and twin heavy bolter and single lascannon each
3 gatling / 2hotvolley/ stormbolter tauroxes
So that's a solid little pack, I think, BUT.
DKOK grenadiers fluff out as the scions assigned to gaurd / work with the tank scions. So this patrol, its all about the most scion-y tank I could imagine.
1
dkok marshalls with hotshotlaspistol and chainsword
leman russ master mechanic plasma tank commander with executioner (how scion does THAT sound an executioner plasma cannon for those days when you want to execute stuff) plasma cannon and dual sponsons plasma cannons and because its
dkok, I believe I can even stick a plasma cannon in the front of the thing for a crazy amount of plasma with my plasma. and stormbolter.
engenseer
squad of 5 stormtrooper grenadiers with 2 plasma guns and 3 hotshotlasguns (casue the sarge can carry those in "tanker scions" apparently) = 358
What this does? Well, it sneaks in the air alphsa strike capability -- you can move forward all your stuff, precision drop out a 10 man squad on turn 1 right beside the enemy, hand it
FRFSRF and gifts of the mechanicum. That's a nice anti-screen surprise for the enemy, when you also add in the 34 inch threat ranged tauroxes and the "anything on your board is mine) 3 flyers. Since heavy bolters are about to go to +1 damage, those 18 shots are much better at chewing through certain popular army infantry if its not in cover.
-- but its MUCH harder to kill 6 transports (3 of them -1 to be hit flyers of higher toughness with 14 rather than 10 wounds) than 4.
I think its a VERY scions in a tank sort of tank, the plasma. Using
DKOK is a lot like using scions, only that little squad of 5 with the tank in the patrol, they are marginally cheaper than scions and can be done up very easily by simply putting no backpack on the scion body, if you can't get the raumjager where you are. Instant carapace soldiers with hotshotlasguns and plasma guns!
I concede the point about melta being a better fit there, though, except of course that my own army actually exists, and my new shiny (still unpainted) raumjagers have plasmas, not meltas, in their very inexpensive kit.
This isn't my usual list, I confess. I prefer to sprinkle in an inquisitor and a psyker to back up my scions in a pinch, a commisar and an astropath. but I DO like this list, a lot, may I steal .. .er .. adapt .. your idea?

Although I am simply laughing as I think of all the plasma that one tank can put out with its (dear god) against a 10 man unit?
2d6 on the turret (minimum 3) and 9 more shots (cause min of 3 x 3). = lots of dead marines if they bunch up.