Warning: this is a "theoretical tactics" article. In other words, it's an article in which I spout off an a subject having never used the tactics described.
I have been thinking about the utility of Stubborn in Sixth Edition.
In Fifth, it was largely panned as useless when compared to Combat Tactics. It was better to attempt to break off the fight and auto-rally in Fifth than it was to stay in melee and get pummeled repeatedly. The only real risk was being chased off the board due to the 6" proximity rule for rallying.
Marines rally automatically in EVERY situation in 6th, which really calls the utility of Stubborn into question now. I've been wracking my brain trying to think of some ways to make Stubborn into an advantage, instead of a disadvantage.
Marines can only acquire Stubborn in two ways: Pedro Kantor or Darnath Lysander.
Kantor allows Sternguard squads to be scoring units, but does NOT allow them to be taken as Troops. Your army will still contain Tactical or Scout squads. He also provides a nice +1 Attack bubble (but it won't stack with an Honour Guard banner). Kantor is "ok, not great" in melee. he is a safer bet in 6th than he was in 5th, as he cannot be singled out in melee like he used to. One Dreadnought punch in Fifth would routinely hose him before he did much on return. With challenges in Sixth, his life expectancy is a bit longer, especially if he's got a squad Sergeant alongside him to soak up powerfist-armed challengers. Pedro can rampage through non-character models with his three powerfist attacks while Sergeant Nobody dies for the cause.
Lysander only boosts the unit to which he is attached by granting them Bolster Drill, a reroll to hit on all bolter-style weapons. He's also an absolute house in melee with his Eternal Warrior rule, S10 hammer, and 2+/3++ saves.
So, once you've taken one of these characters, how do you use Stubborn? Here are a couple of possible ideas:
Extend the life of combat squads.
Combat Squads is a great rule for instantly doubling your unit count, be it for objective holding or increasing the number of potential enemy targets that can be engaged. The problem is that 5 Marines can only do so much, and one of those resulting combat squads is Ld8. Taking even two casualties from a small squad drops your chances of staying in the fight dramatically. You're suddenly rolling against Ld6 instead of Ld8. The ability to keep a couple Marines holding ground leads nicely to the next point.
'Tarpit' is a dirty word to many, but it's actually a viable tactic in the days of 6th. Objectives are everything now (and they were in 5th as well), and securing them against attackers is vital. A tarpit unit seeks to lock up an incoming enemy in melee, and keep them there until the game expires. A Marine unit that holds til the last man is easier to achieve when you're not taking cumulative Ld penalties for losing an assault. Of course, is this any more desirable than using Combat Tactics to fall back after your opponent's turn, auto-rally, and then open fire into the unit and charging it again?
That's really the best I can come up with in regards to uses for Stubborn. Can you think of anything else, or is Stubborn more of an impediment than a bonus?