Hi Juan and welcome.
Basically, what is the verdict?
Is the Fujinon 16x28 better or worse than the Canon 12x36MKIII?
Terrestrially or for astronomy?
Is that your telescope in the YouTube introduction?
My 18x50 IS is almost 20 years old and has worked almost perfectly all this time.
If the button is pressed it stays on for about 5 or 6 minutes.
It shows some elongated coloured stars if the stabilizer is near the end of its range, but I switch off and switch on again after the image is central, It takes two seconds.
However, I don't know how a new 18x50 IS works or whether it has modified IS.
Mine seems to be a very good example.
Some Canon IS binoculars don't like lithium batteries. I use white Eneloops or lithium throwaways.
Some Canon IS could not take slightly larger Eneloop Pros as the chambers were not big enough. This problem should be cured now.