I think the Alchemist kit needs a bit of tweaking, because without the potion effects, the kit has no weapon or armor, and is extremely easy to finish, despite any killstreak you had before.
1. Make the potions last longer. The kit isn't too overpowered, but once the effects disappear, you're dead. I think the potions should last longer, because logically, you don't lose your sword magically, or have all of your armor break at once (unless you're a healer,) so, I don't believe this should be the case for the Alchemist. The potion effects should last either an extremely long time, or something like 8:00, as 2 1:30 potions of Strength 3 will have you screwed over, and that goes the same for the Resistance 2 as well.
2. This is more of a convenience thing, but I think it would be cool if all of the potions were stacked into one. This way, it would take a significantly shorter time to get into the arena, and you could call the potion(s) "Alchemist's Potion" or some other cool name.
I think these changes would be beneficial to the kit, as it would make it more playable, as well as make it stand out a little more. I think it would appeal to more people this way.