T20 (Traveller D20 Version) has its own hybrid system based on 3.5. There are several changes; Stamina and lifeblood instead of just hit points, addition of extensive vehicle rules and of course starships.
The Twilight Sourcebook, which is on hold currently, is based off the T20 system. Both systems have a much more realistic combat model. Almost every time you get hit in combat you are going to lose lifeblood (Which is equal to your Con score). Armor helps reduce damage but not all. The weapons mechanics, particularly auto-fire and burst rules are the best I've read (D20 Modern, Spycraft, Star Wars). T20 has almost non-existent melee and hand-to-hand combat. Twilight will have an updated form which is closest to the Star Wars system. Nothing fancy, but the ability to dish out more damage, trip, throw, disarm your opponent. There are also rules which allow knockout blows and one shot kills with the proper feats and skill levels, and an unaware target. The system has enough detail to satisfy a CQC buff, but not enough to bog down the play.
Unlike other modern and future games, Traveller and Twilight is fatal to the movie hero character. If you dash out in front of a machinegun nest, or stand around to return fire in an ambush the character will die. If you go toe to toe with an armored vehicle, the character will die. You get shot more than 2 or three times, dead. A single crit with a good damage roll, dead. The use of cover and concealment is vital to keep your character alive. It is a down and dirty system. Powergamers may not be pleased since they won’t be able to simply wade in and kill the enemy. Detail buffs will find it just what they want. The emphasis is on roll playing and living a story.
Hope this long winded answer helped.