I think Krama's 360+ speed are a bit to high. I have less speed on my Arbiter, 348, and win the speed race in Gold 5 most of the time.
I guess speed teams are really getting slower. They are not the meta anymore. The players with the best equip and champs don't build speed teams, and the players that build them - like me - don't have the best equip. So the average Arbiter speed team you will face in arena is slower than it was.
If you run a speed team, I recommend a champ that can control the enemy going as second champ directly after Arbiter, like Umbral Enchantress. That allows the rest of your team to be much slower, the enemies may even cut in, no problem if they are provoked.