@stukapooka Very good points. 🙂
Honestly, some of my opinions would be biased, for instance:
I suppose I think that way with Scientist as I normally play a passive Steam Blaster loadout, which means I will focus on healing as I prefer to do that, but really enjoy the Steam Blaster attack, so I only attack enemies if they get too close to our team. It's a good way of clearing out enemies that are getting too close to the team.
Shogun-Guard is such a fun upgrade for me to use, and my favourite Legendary Upgrade, however I do find it does not seem to be as powerful as say, Brainium Basher instavanquishing plants or Steam Blaster dropping groups of plants at a time. I totally agree with that one that those upgrades are much more powerful (and need to be balanced). At least I do not have to be concerned about using "broken" upgrades as in way too powerful while using Shogun. I find I am much more accurate with Shogun-Guard than with other characters, can get revives quite easily using the shield and being able to attack with the shield up is a big plus for me.
I should probably do another tier list soon.