Yes I have started using the downvote/rewards redistribution tool a lot more since HF 21 and have been in heavy discussions this past weekend about it all.
On one hand you have "easy cases" such as massively over rewarded posts (I mean let's face it, on the whole, is any post really worth that much more than $50 around here?) that have a couple of lines of text and maybe a picture - this used to be prevalent pre HF21 - and plagiarising, spam, things like this where the downvote tool can be easily applied.
If that's what the tool is for, these "easy cases", then yes I think we all agree that it will be a good thing.
The grey area is based around perception of quality content if the downvote tool comes in to effect. For example (and this is just a fictitious one for argument's sake) - Someone may write something they have put a lot of effort in to (e.g. travel post in not their mother language) but it doesn't come across as high effort to someone who has their downvote trail set up and then the author gets hit with several flags from 20 random folks. No one has read it other than the trail owner and so this author is subject to a horrendous experience for something they may have spent hours writing.
Add to that the people following the down vote trail may have actually appreciated the post if they read it and the effort put in from the author for writing something in a different language that isn't their native one (in this example).
Don't get me wrong, I can see the advantages of having this tool and not poopooing the effort that must have been put in to make it. I'm just trying to see all angles here