While I admire how you try to make the physical changes visible, I’m going to have to vote no on this one completely. On a gameplay perspective, I feel like having different speed-health ratios would create a mess of things. First of all, if some players have a higher base movement speed than others, then how are you supposed to design maps? As we know, maps are built based on the movement speed of players. The jumps, distance of cover, size of power areas, etc. are all based off of how quickly a player can get from point A to point B.
If the maps are based off of the fastest possible movement speed, then any player who does not pick that type of character is instantly at a huge disadvantage. Sure, they have a bit more health, but they won’t be able to get to cover as quickly, won’t be able to make the same running jumps. That means that they won’t really gain much advantage from their extra health. If they can’t make it to cover fast enough, then they’ll get shot more, and therefore not gain any advantage from their health. And what if the maps are based off of the slowest possible speed? The bulkier Spartans don’t have any disadvantage, but then the faster Spartans have a supremely large advantage. They’ll be able to make jumps and plays that were never intended from the map designers, creating a large imbalance. And if the maps are designed around the average Spartans? Slower ones are still disadvantaged, and faster ones get more advantage. We would end up with poorly designed maps.
And nobody should be able to swap weapons faster than others, or be able to strafe more quickly. In the heat of the battle, the winning player should come out victorious due to having superior skills. Is it fair that I win in a battle simply because I could switch to my secondary weapon faster than you? Or is it fair that you beat me simply because your character can strafe faster than mine? No, it is not. Look at it this way, if two players are exactly evenly skilled, then statistics say that both should win exactly 50% of the time against each other in a BR duel. However, if one person is a short, thin Spartan, and the other is tall and stocky the short Spartan would end up winning far more than 50% of the time. Why is that? It’s because he simply has a trait advantage that the other guy does not have. It is unfair, and unfun.
And then there’s the visual aspect of it. Making your Spartan stocky or thin? Fine, I can accept that. In fact, I would love it, as long as there’s no gameplay changes associated with it. After all, it’s the same deal as changing your Spartan’s gender. You have the same hitbox, therefore things are equal. But height? No way. People would always be picking smaller Spartans, since there would be no reason to make yourself a bigger target. And then, at that point, what’s even the point of having different sizes? Let’s just stick to one height.
Therefore, my final answer is no. Like DecepticonCobra has said, if we want to have different heights and sizes, they should be limited to different species that appear in different gametypes, like Invasion.