system
Given the following post, respond as if you're commenting on Reddit:
human
[Halo (Bungie/343 Industries)] Do Spartan-III's make Spartan-II's obsolete? Do S-II's have virtually any advantage over the S-III's, at all?

I've lately been reading a lot of 'Spartan II vs Spartan III' style threads on various forums, and the consensus I'm getting is that S-III augmentations actually put them on-par with S-II's, combat-wise, and that the only reason that we notice any difference between these generations is due to the financial need for S-III's to use weaker SPI armor instead of the expensive MJOLNIR that the S-II get to use.

So if the S-III augmentations are just as potent as S-II augmentations, then why are the S-II's considered 'non-expendable' (Much unlike the S-III's), who theoretically could replace them rapidly, since both generations possess similar physical attributes and abilities?
gpt
So in terms of say a modern military logistics the 3s are better in most regards. The cost of making them is offset by their effectiveness and they're still replaceable. They benefit from nearly 20 years of spartan 2 development and research and have a wider pool of possible recruits. They can even skip the child soldier aspect and train a 3 in about a year compared to the seven a 2 needed. 

But there are trade offs as in everything. Alone a Spartan 3 isn't going to win a battle. They're tough and capable but only marginally ahead of a standard special forces soldier like an ODST. They work in teams and need additional support to pull off their missions. Because of the desperate nature of the war that created them they also lack longevity. Most are theorized to be sterile and suffer from implant degradation and severe cellular defects after a few years. When deployed like suicide troops and with a short operational lifespan 3s sacrifices for cost and production speed are reasonable. Long term they're unsustainable and will result in a negative loss as the older 3s decay or require expensive and intensive medical procedures to lengthen their operational lifespan. 

2s by contrast are ridiculously expensive. Each 2 takes over 7 years to train and has to be brought in before puberty from a small pool of possible applicants. Ethical dilemmas aside they're the cost of a warship each with no guarantee they'll survive training and augmentation. But a 2 is a fortress on the battlefield. Able to turn a tide single handedly and operate for extended periods of time without support. Nearly 35 years after coming into operation they had only improved combat effectiveness rather than decreased. The oldest serving 3 that is known was around 5 years since coming online and had severely diminished capabilities making them equal to standard special forces. 

In a paper scenario the 3s are soldiers meant to be used and spent as needed to accomplish the mission. Taken from common materials and molded quickly and cheaply into a usable but ultimately expendable form. The 2s were flagships. Entire battle strategies planned around them. Each one a massive cost in time and resources but used sparingly to avoid losing such an investment needlessly. 3s could and were used in desperation to stave off extinction. 2s were meant to be used for more than just fighting and intended to be the culmination of human warfighting technology. 

Neither makes the other obsolete as they fill overlapping but distinct battlefield roles. While the 2s were better in every way they cost too much and took too long to be mass produced. The 3s were lesser but cheaper. A trade off made to maximum battlefield usage while limiting the resources spent on them.