Without owning either Cortex or Sentinels yet, how similar are they? Is there anything from Cortex that can be used or mined or swiped to improve Sentinels or are they there own beasts that this is not really the case?
I have no idea what you are talking about. What's Cortex?
Would appear to be this:
https://www.cortexrpg.com/compendium/explore-the-rules/
both Cam and Dave (the designers GTG brought in for SCRPG) have been designing Cortex for ages, so there's a certain amount of squint-and-you-can-see-it similarities (like using multiple columns of rated dice traits to build a dice pool, for instance). but. Sentinels is much more Fatey than Cortexy. with a really clear "make it feel like SotM" directive thrown in. for what it's made for, I think SCRPG is better than Cortex. but Cortex is dramatically more flexible.
I'm actually not certain there's a whole lot to glean from Cortex to bring into SCRPG. you could certainly make a different style of game using SCRPG's min/mid/max system by introducing different trait sets (replace powers and qualities with things like values, relationships, roles, etc). it might be possible to try using stress dice instead of hp. it might be possible to introduce hitch mechanics (you get a consolation prize for rolling ones).
but honestly I'm not sure it's worth futzing too much. SCRPG is a very specific experience built from a very specific set of mechanics all leaning on each other to support that experience. that said, as a Cortex player, I'm definitely thinking about stealing SCRPG's GYRO track and the guided character building, because those are utterly brilliant.
Besides FATE and Cortex (although started before FATE core and Cortex prime) the other game system they admit to having inspired them is Dungeon World/Powered by the Apocalypses.
I mainly know Cortex from the Margaret Weis Marvel super heroes RPG and remember Dave or Cam talked about the very poor character creation rules in Marvel
They have also said that they would add new optional rules as they add books so Stress dice and Hitch(s) might an add on modal in the future
Having both...
Both are are ratings in die sizes, both use dice tricks (count some, not all; reroll if...), both have provisions for creating bonuses and penalties...
Cortex Plus/Prime. is one die from each of 3 to 7 categories (setting/adaptation dependent), keep two of choice, sum the kept for action total; unkept non-1 with most sides sets effect (Damage, temporary complication, possibly also scene boost assets)
SC is always roll 3, 1 per category, for PCs and Villains, 1d for other NPCs
There is common lineage - Cam Banks is in the preview pack.
SC is kind of half-sibling of both Apocalypse World and Cortext...
Cortex results really boil down to fumble, fail. success w/no or d4 result, success with d6 result, success & d8, success & d10, success & d12... some flavors add high roll (>5 over opp) as granting a bonus. Most rolls are opposed pools.
SC has 5 discrete result bands (≤0, 1-3, 4-7, 8-11, ≥12) . Most rolls are unopposed.