Not going to add much but just confirm some suggestions -- having went down a similar route about a year ago. Buy the Mantis, and dont pick an Erica Synths Quad VCA. That said, if you are still in the market, I have both for sale 😉
Recently, I acquired a Mantis case and a Tangle Quartet and have absolutely no regrets. Another note on the Erica VCA... the channels don't fully close. Erica Synths stated this is normal operation. Extremely annoying to have a quiet leak of sound when you want it to shut up.