I like every single gate, from the 2nd to the 8th. My Gyojin is naturally 1.5x faster and has superior strength, so it's almost as if i'm in 1st gate state all the time, so that doesn't really do anything for me other than the +5 DMG which would be kind of pointless to use, as it doesn't wage much diference.
The 8IG don't seem to have (imo) many repercussions. As a 'user' I can deal with using B ranks only for 1 turn after my gates close, and low stamina for 2 turns? I think I can keep myself alive through those 2 turns to regain my full strength. One thing I don't like is the 8th Gate restriction, you die immediately afterwards, but that's a given. What itches is the fact that it only lasts 2 turns, that's practically nothing. Three turns? that's respectable.
On that note, you know that Will power of the Heart technique right? the one that let's us pull our inner wills and keep on fighting when we were supposed to die, for 3 more turns. Can we use this after the 8th gate closes? thus earning ourselves 3 more turns of life. I don't see why not.
I bet you expected a definitive answer from me, didn't you? Well, I'll have to disappoint you on that one. The truth is; I honestly don't know. As far as I know that's never been tried. Is it something I'd do? Nope. Want to know why? Because the second you use the Eighth Gate in a fight one of two things has happened: 1) you want to show off by killing an inferior opponent, in which case you've learned nothing from me, or 2) you need a boost to defeat a superior opponent, in which case, yeah, you've learned nothing from me.
I don't like risks. I've done some really risky things in my RP career and it has
always come back to bite me in the ass.
What do you do when the opponent opens a Gate that'll kill him in a couple of turns? You dig in. Speed on NB is different, as you no doubt know. Power is measured in rank. You
can defend yourself against the Eighth Gate and people
will do so.
But yeah, I'd say that Willpower of the Heart would extend your life. It wouldn't keep the Gate open, but it'd keep you on your feet. It makes sense, especially after we saw what happened to Guy in the manga. He didn't exactly die.
Anyway, 1.5x natural speed 'cause you're a Gyojin and the 1.5x bonus from the first Gate. That's not bad. It adds up, you know? If you're really hardcore you can keep the Gates going for a looooong time. Open a 'higher' one every third turn to keep the blood pumping. It'll be a slow, but deadly ascent.
What's the downside? Well, once the Gates close you're done, unless you're an EIGM; then you get another try.
Still, a war will usually see you fight more than two battles. the Gates aren't suited for every type of fight. You'll know when to use them and when not to.
Let's do a scenario. Say I'm a Hyuga with all the toys... would you open the Gates on me?