100% YES (does anyone really answer no to this?).
To be honest, my answer would be no.
Don't get me wrong, I'm glad that there are still Spartan II's around, but I dont want them to be around in Infinite. 3 invulnerable characters cause several issues in my opinion. Well, the first one already has been mentioned - they are invulnerable. Means that your decisions are not as important as they should be, you can play way more reckless and the battlefield gets way more chaotic.
Another issue I have is: So, you have 3 characters all the time around you. You always have to give them some dialogues in any given situation, which totally kills the vibes of mystery, discovery and adventure in my eyes. Either you build them up, or they get labeled as boring characters.
I mean I don't know how to put in words, but I'd rather just have marines as an ally and not specific characters. Characters that can actually die, so my decisions are more important. If I play reckless, my allies will die. There's always a feeling of discovery when you travel alone or with NPCs that have less knowledge than you.
Maybe there will be a mission (only time will tell), where you have to engage a "huge battle" alongside invulnerable characters (whether it's a spartan or Arbiter) but I really hope that it's limited to one mission.
I'd really like to discover things on my own and I don't really need reactions from other characters all the time. Let the terminals do that.
This doesn't automatically mean that Infinite shouldn't flesh out any given character. But they should be used at the right time & in the right place.
Before someone comes up with Reach as an argument - Reach was from the ground up labeled as this "huge battle", where you had to fend off the largest Covenant invasion of all time. Unlike Infinite, it's not really about discovery / mystery on a foreign planet.
But this is just my personal opinion.