It's fairly common practice with Flow to run type-checks as a part of the build or test step in a standard build/test/deploy workflow in CI, which largely removes the possibility of bad merges arising from type errors. With TypeScript, using the TypeScript compiler, type-checking would simply happen in lockstep with your build step, whereas with the new Babel preset and a separate type-check process, you still have the option of running them in lockstep as 2 separate commands, but you also have the option of running them as separate jobs in parallel, likely leading to significantly shorter build times. It's definitely going to be a huge net improvement to my own workflow, but you're certainly free to stay with the status quo if you feel it suits you better.