This topic is definitely at the front of our minds. Launching the migration with feature parity to the current site is "phase 1", solving this problem will be addressed in a subsequent phase. Trying to find the wheat amongst the chaff of a 100k post thread has been diyAudio's bugbear for a long time, and we are very much looking forward to finding the best solution possible.
Some kind of signal/noise identifier has been suggested, and I have seen other sites where you can use a slider to dial in the level of noise you would like to see. I'm not suggesting that will be our solution, but just giving an example of how another site has tried to address this.
In a word, yes!
It's very often I want to like a post to let someone know I've read it, let them know I concur, or to say "thanks". Having such a button means a lot less "me too" posts that add noise to a thread.
Some background: We did have this for a week or two about 10 years ago. The system was quickly gamed for the wrong purposes by warring factions and was disabled pending a better implementation.
We'll be slowly introducing reactions and see how the community uses them. If we can find a way to make them work without them creating negative vibes they'll stay