@stukapooka I haven't posted Space Cadet yet although it's written up in Word (I want to post 1 per weekday so we have time to talk about these), but I mention there that the Space Cadet can lose her homing and I'd not mind one bit, and she's my favorite new character in BfN. She doesn't need it, and some variant ideas I have couldn't use it anyway.
The Peashooter homing upgrade is a bad idea, but it also either doesn't work at all, or doesn't work very well.
I feel that legendary upgrades could be turned into variants instead with some work and simultaneously give us some variants that stand out more from the standard fire, ice, toxic, electric, etc. variants and give us more like unusual ones. With some balancing of course.
As for upgrading the turrets (and as an extension of that, the Guardians), I'd not be against the idea, I actually did like it, but the last upgrader got all the credit for the bot's vanquishes which was a problem. If they wanted to bring that back, they'd have to either only let the original builder upgrade their own turret (not a fan of that idea), or everyone who built/upgraded it should get credit.