As I've delved into Savage Worlds and the benefits and issues therein, while simultaneously reading more on Warhammer 40k rules, it has solidified an inkling I had.
Savage Worlds developed in part as a miniatures tactics ruleset almost exactly like WH40k.
Where GURPS began as an exceptionally in-depth combat system that grew into an incredibly comprehensive, simulationist tabletop RPG, Savage Worlds seems to have gone the other direction, starting as a Fast Dice system with minimal bookkeeping to track character's vital details and adding options for elevating a simple tactics character to Roleplaying Character status. While I know the system evolved in part from previous games made by Pinnacle that work similarly, the incredible lack of alteration required to use Savage Worlds as a minis combat system is unlikely to be accidental.
In both WH40k and SW, typical characters (Extras in SW parlance) have 1 wound before being removed.
Most Named Characters (Wildcards in SW) have 3 wounds.
Both systems mitigate low "hit points" with a roll to wound based on the unit's toughness.
Both systems use a flat "to hit" roll based on skill for ranged attacks vs a fixed target modified by cover. Both systems utilize a simple comparison of melee skill to determine who can hit what in melee. Both systems effectively lock you into melee until one side retreats, AND consider pistols as a melee weapon in close combat. (WH40k locks you in combat, and a side failing the Leadership test to continue fighting is hunted and destroyed as they try to flee. SW grants the party not retreating a free bonus attack on retreating enemies).
Both follow the roll to hit, then to wound. Savage Worlds differs by adding a sub-wound level of Shaken that stuns a character if the to wound roll is only barely successful. WH40k has an extra roll for armor save, this is rolled into the To Wound in SW
Both systems permit a 6" move action and a single action on a turn. That run action is handled via a d6 roll for extra distance in both, barring special rules to increase die size. In WH40k, there's an alternative option to charge into melee which usually grants first-round bonuses for the fight, while SW permits you to run but incurs a -2 multi-action penalty to any further actions.
Both have morale/leadership rules to resist the urge to abandon the fight upon taking set numbers of casualties.
Both systems assign ranged weapon's reach based on kinematics (modified by accuracy or effective range, if relevant), rather than actual projectile reach. In WH40k, pistols and shotguns get 12" reach, rifles get 24", stuff like LMGs get 36". In SW, pistols and shotguns (non sawn off) get 12", rifles get 24", and LMGs get 30". In WH40k that's all the range you get, in SW you get two additional range bands (doubling each time) with a -2 and -4 range penalty.
Both systems modify odds similarly. WH40k uses differing success numbers on a d6 (2+, 3+, 4+, etc. 1 always fails), savage worlds instead keeps the target number (mostly) the same and uses progressively larger die type (d4, d6, d8, d10, d12).