I love Rails vision about how to do full stack web development. It is a really good abstraction, that hides unnecessary technical complexity and lets you focus on solving business problems.
A lot of people here complains about Rails performance, and that is one of the reasons why I use the Grails - Java framework. It is not as polished as Rails, and has a few sharp edges, and it has a much smaller community which is still super-friendly and awesome. Grails however can still take the advantage of the enormous Java ecosystem. You have a library for about everything. And many of them is of really high quality too.
I have for the last five years built three successful startups with Grails, where the last one now employs 100 people. Grails has been really helpful here, as it has made it possible to move fast and add,fix,improve,break changes quickly. For my last startup Rails would most likely have struggled with the amount of data we are dealing with, while Java is hardly sweating. It is not something Grails specific, but still a part of the Grails application, that is why I mentioned Java.
My last startup, which now employs over 100 people didn't use React nor Angular either in the beginning, just vanilla Javascript. More speed, less complexity, less errors and so on. We use React today, but that is because new employees really really wants to work with. And developer happiness is really important.
You may gave gotten into Grails at a better time. I more recently attempted a project in Grails and it was a disaster. In fact it was my worst framework experience ever. Mainly because completely inadequate sources of information. Grails 3 had been released but the documentation was terribly incomplete so we had to spend a lot of time searching and about every bit of info we tried to look up returned results strictly for version 2. So some really basic things we just never figured out how to do. I’ll never touch it again.
I have used Grails since version 0.42 and I am a bit surprised to hear that the documentation has been incomplete. I have always found it very detailed, though sometimes lacking clarity as any framework documentation would have. Since the early days, the way you build Grails application has been almost identical to how you write and structure your code with the upcoming 4.0 release. Of course if you have used some plugins that has been unmaintained, that could have caused issues with upgrading. But otherwise I have had a great experience through Grails lifetime.
And if you really needed to get "out of Grails", there has never been an issue using the Spring MVC api or Spring Boot with Grails 3+
It is still now distant enough that I can't recall specific examples, but what I had found is that the solutions in blog posts etc. on Grails 2 (large majority of search results) did not apply to or did not work with Grails 3 when we tried them, unsurprising given a major version change, but frustrating nonetheless. I suspect that since you were following Grails's progression from such an early stage, any incompleteness or lack of clarity in the documentation may have not been so obvious to you because you would have been able to implicitly fill in the gaps, but we as newcomers found it totally inadequate. It was often reduced to black-box trial and error.
A lot of people here complains about Rails performance, and that is one of the reasons why I use the Grails - Java framework. It is not as polished as Rails, and has a few sharp edges, and it has a much smaller community which is still super-friendly and awesome. Grails however can still take the advantage of the enormous Java ecosystem. You have a library for about everything. And many of them is of really high quality too.
I have for the last five years built three successful startups with Grails, where the last one now employs 100 people. Grails has been really helpful here, as it has made it possible to move fast and add,fix,improve,break changes quickly. For my last startup Rails would most likely have struggled with the amount of data we are dealing with, while Java is hardly sweating. It is not something Grails specific, but still a part of the Grails application, that is why I mentioned Java.
My last startup, which now employs over 100 people didn't use React nor Angular either in the beginning, just vanilla Javascript. More speed, less complexity, less errors and so on. We use React today, but that is because new employees really really wants to work with. And developer happiness is really important.