Your positive feedback and kinds words are most definitely appreciated here! Your little island sounds exotic. Can I come and visit? : )
It is right of your school/customers to be asking questions about sustainability, and this is something I am asked often when working with schools on implementations. Gibbon is over 5 years old, but if you look at the commit logs and forum comment, you will see I remain the primary actor. Moving away from this situation, and building a community, is one of the challenges of an open source project, especially one targeting education, which lacks some of the tech know how you might find in other industries.
As more schools come on board (and we are currently at around 20 in production, with over 2500 installs worldwide), our community grows. First users, then advocates and then developers. This growth is still in its infancy, but it is happening. As one example, in April we will hold our first Hackathon, where we hope to have around 10 coders together for a day, working on features for v12. This would not have been possible a year ago, but today it is.
Personally I have invested thousands of hours in Gibbon, and it is the largest work of my life thus far. I certainly have no plans to walk away, and will do everything in my power to sustain and grow it into a platform that can stand without me, and that delivers the positives you describe above.
If your school/customers are bold enough to join our community at this time, you will become pivotal in pushing Gibbon into a more sustainable future, whilst getting a mature, stable, feature packed platform for free. It’s a catch-22.
Hope this helps.