It's pretty awesome that you've got something making $1600/mo without any proper marketing. It seems insane to me to abandon that effort for something else. Not to mention, if your next project takes off, you'll probably find yourself in the same situation again.
I would double down on this one. You'll likely have a lot of learning to do, but it's gonna be a good education and possibly very profitable.
But then, only when I received good feedback I thought to proceed with it.
I won't deny, the new thing is definitely appealing because it's new. But you make a good point about finding myself in the same place again.
I've had some good options presented here and I'm leaning towards focusing on rosterbird and try to get a growth engine going and then, maybe, once it's sustainable, I can try new things if I still wanted to.
The smart money though is on the thing that's working. Take the time to understand why it's working, and how it might grow future wise, and user wise. This is not fun like programming but makes the things you build more successful.
At the same time put some limited hours into keenly. It makes a good distraction, and we all like a change from time to time.
Always remember that building things successfully takes multiple skills. You've got the programming down, but learning the rest can be just as satisfying.
And don't be scared to ask for help. There are lots of successful people around you who can help if you just bother to ask.
Focus on the product that’s making money with minimal effort. You will learn a lot in the process (it may make sense to bring in some contractors to help you along in certain areas). Maybe you find you really don’t want to take that any further, at least you’ll have a much stronger understanding of the product, market, etc which will help you sell it off for a higher price and fund focus on the next thing.
No other words are necessary.