Makes a lot of sense balance-wise, I agree. The thing that lead me to suggest this is how I would always recruit a Hybrid Lord from any land-castle that I have due to being so much better than a Illithid Lord: Cost-wise, smaller, has feet slots, same mind-blast, not magical-I.E.: not vulnerable to magic-creature only spells/weapons, only disadvantage is that they have 15 less magical leadership and they have less HP, MR and STR. Though isn't that the point of hybridization? Mixing your race with another's to create a more efficient breed species? Reducing both your own races strengths and weaknesses by creating a hybrid of a lesser race, but still being stronger than the race you're mixing with.
The Hybrid Soldiers also have one other limitation that they have over the usual Illithid's that people recruit (the non-armored/life-draining ones). They're limited by resources... though perhaps raising their resources to 22 to match the Illithid Soldiers would make sense(?), either way they become roughly equivilant to Illithid Soldiers. With your mod though, supplies become virtually a non-issue, even for larger, bigger appetite (what DO Illithid's eat anyway?) Illithid Soldiers compared to Hybrid Soldiers. Also... themeatically the entire purpose of cross-breading in fact IS to become more adaptable to this new world they're attempting to enslave. Thus the advantages of the Hybrid as opposed to the pure-blood.
These were all thoughts that I had when thinking about the Hybrid Soldier conceptually compared to the Illithid Soldier. If we could mod their mind-blast to perhaps be lower-strength than a normal Illithid it would make sense. As it stands now, star children are still a much better investment by far gold-wise, but limited due to only one per turn per keep and needing a lab.
Now... I do agree with you that the change to Hybrid Soldiers would increase the effectiveness of Ryleh land-recruited units since they're currently limited on their land-units to only produce leaders and front-line fodder types. The food limitation however is considerably lessened with this mod, leaving the higher str, higher HP, Illithid's still superior due to their being 60% more food available.
I've been experimenting with a game (single-player) with the Hybrid Soldier changes I mentioned, and it feels pretty good balance-wise so far. Then again, I mostly play single-player so far so it doesn't really factor in as much. Them being better than the under-water recruitables in some ways encourages Ryleh to push out of the water and solidify on land in order to create a cheaper, if weaker, army of hybrids to support/supplement their pure-blooded Illithids. Also, this forces Ryleh to solidify assets on-land (where they can't hide from their land-enemies) in order to get Hybrids (which were of very little use before this mod except for the Hybrid Lords and Star Children).
A quick hypothetical cost-breakdown:
Concept Hybrid Soldier (45 gold, 18-22? resources): 30 gold mind blast weapon, 15 gold 10 morale, +5 hp, +1 str, -1 def, +2 natural prot - non-magic unit. 2/8 move
Eqiupment: Plate Cuirass, Trident (Why aren't ANY Hybrids given helmets anyway? Easier access for Illithids to suck their brains out if they get hungry I suppose)
You get a cheaper mind-blasting unit, that will get cut apart by cross-bow fire (potentially dying in one hit), with lower morale, but is smaller (takes less to feed and fights in tighter formations) and slightly cheaper. Also, takes normal leadership instead of magical.
Illithid Soldier (55 gold, 22 resources): 30 gold mind blast weapon, 25 gold for 11 morale, +5 str, +19 hp, +1 att, -3 def, +5 prot - magic unit. 1/7 move (why are they 1 strat move anyway? Normal Illithid's are 2/8 and Illithid Lords are 2/7)
Eqiupment: Plate Cuirass, Trident, Helment
You get a larger, more powerful mind-blasting combatant who would stand up to cross-bow fire (2 solid hits), and packs more of a punch in melee after all the mindblasts are gone.
So basically what we're looking at is the fact that Illithid Soldiers are so tactically bad to begin with (except for HP/str/prot), that except for the fact they're armored and have a mind-blast, they're not worth their gold/resource cost. This makes the Hybrid Soldier seem glaringly powerful in comparison, but only because the Illithid Soldier is worse in the ways that in practice are bad as opposed to on paper. If the Illithid Soldier was increased to 2/7 moves, and perahps given 1-2 more defense they would become better than a Hybrid Soldier in practice (thus justifying the +10 gold cost for a higher hp/str/mr/morale unit). It's partially the strat move, size and extra resources that makes the Hybrid Soldier looks so much better.
Hmm... perhaps they could be balanced with an extra supply requirement? #supplybonus -1 or -0.5 for example? That would put them closer in line with the rest of the illithids as far as supply limitations.
Anyway, I've babbled long enough... take my opinions with a grain of salt as I'm more expressing myself than anything else. In the end, I understand that Ryleh, out of any nation, needs the least help as far as their units go just because of the mind-blasting attacks, though without this change the Hybrid Soldiers have very little, if any, place in the armies of Ryleh compared to the fixed (non -4 attack) Hybrid Troopers.
P.S.: I appologize for my long post... appreciate you reading it, regardless of whether anyone agrees or disagrees. Feel free to dismiss the ramblings completely but I felt the need to explain my full reasoning for the suggestion.
Resok