Very cool!
I'm looking forward to it. The concept is very interesting.
A few more ideas:
The start is a bit slow. If all Speed stats were doubled in the beginning this would feel more dynamic. (The start health of enemies in the first X battles could be changed to compensate for it)
The HP text on the healthbars is very small and blurry (at least on my screen (fullscreen)). Hard to read.
Right now the amount of new items feels too spread apart. Maybe you could add consumables, to increase the loot factor. This could be health potions, (temporary) damage up potions, (temporary) speed potions, revive potions and upgrade potions that raise the level of an item.