Hello! Actually we had the same issue and decided to migrate everything to Node.js and ExpressJS! And I regret it. Not because Node or Express are bad. Actually they are awesome and powerful frameworks that we use for almost all our microservices needs. But we regret it because the time we spent doing this conversion (development, testing, integration testing, new staging and productions servers, and environments, etc.) vs. the returns we had in terms of practicality or modernization, were not justifiable. The truth is that, even though Grails and Groovy are not as famous or are as widely adopted as Node and Express, they are robust, well maintained, designed, and implemented frameworks that have everything you should need for almost every need and they get better every year. So, if I were you, I would stay with Grails and Groovy for existing projects that already were implemented with those technologies. However, for new ones, mainly for community, and developer acceptance, I would go with Node.

Hope this helped!

Like everything in software there are trade offs and gains. For one if you are already proficient with JavaScript on the front-end it will make sense to use Node.js on the backend as it will have little or no overhead in terms of getting productive really fast.

On the other hand I believe Grails should come with batteries included and you wouldn't find that easily with Express as you will need to assemble dependencies and figure out a folder structure that will work for you and your team. That's where you will need something like Sails.js to level the playing field. It's built on top of express amongst other awesome tech like Socket.io.

In conclusion it all depends on you and your team level of appetite as well the stakeholders if all parties want to do the change then oh yeah go for it!