I'd like to see Sunflowers being a bit weaker at healing than they currently are, in particular self-healing. I use the blossom upgrade on my main build so I can self-heal and self-overheal if I only have one target in range. Add that to the vampire flower upgrade and sunny side up, sunflowers are very annoying to fight against in PvP and can keep themselves alive to an extreme degree.
As for Scientists, I'm not as sure, although I'd like to be able to fight a bit better while healing, right now you can use the heal thingy and fight but if you use the healing hose you cannot. He's far weaker at self-healing than the sunflower is, that's for sure.
On a related note, I hope they also adjust that hardened upgrade for Acorns. +50 health is too much for the tiny character and when stacked with overhealing and especially if the sunflower healing them has cocoon, they can have a huge health pool on top of being difficult to hit and mobile.