Well with a chomper like Chomp Thing or Toxic Chomper you can't really expect to get kills with your spray attack since they are so horribly weak. I hardly see a digestion upgrade on them as useless. All Chompers are known for, and most people probably use, their burrow ability and chomp, so being able to quickly eat your enemy, then goop or burrow again would be ideal. Also they can't just give us damage upgrade or anything of the sort off the bat, it would be too easy and no one would promote, or just simply do it to pass time.
And as for your speed upgrade. Well as a cactus you may want to get to your sniper perch quicker, so a speed upgrade would help. Maybe not by a lot, but it would.
