If there's a spring way and a Grails way of doing things, we've been choosing the spring way more often than not. I'm glad that Grails has been moving more and more towards a standard spring-boot application with the "glue" to bring together the rest of the stack nicely. Anytime we find a spring-boot issue, there's tons of help online for it. If it's something specific to Grails, it can be difficult to find answers.