Hi Debbie,
Great to see things are still going well for you. Its not a combination I would recommend usually, however I trusted your judgment on this particular Puffer and it seems I was right to do so...certainly so far, really pleased for you!
Vincent, your tank and its occupants is truly fantastic! I'm particularly loving your wide bar Myleus. In all fairness all the fish look so healthy and happy.
This hobby is not black and white, that large Flyriver Turtle for instance could not only take chunks out of the larger fish such as the MBU but could literally swallow half of them whole! I have kept many Flyriver Turtles myself, some were fine with fish other were not.
Its a case of being extremely cautious, feeding all the inhabitants well, providing adequate space and not forgetting that the system needs adequate amounts of bio media and flow to cope with the heavy feeding regime. Animals and fish can be just like us in some ways, if they are getting their food served on a plate at specific times then why go hunting and chasing it around, doesn't work with all predators as some kill more than they can eat just for fun, but as we see so many times, people getting away with combinations that really shouldn't be working.
At the end of the day its always a risk!