I have a futura mk2 and I have had very similar experiences with the glued seams. My welded tubes have held up very well, but I did pull apart all of the seams that would come open without damaging the underlying fabrics PVC coating. My floor did not come apart all the way around and sections of the transom to tube seams had been previously repaired. I glued everything together and have not had issues where the seams were not separated and reglued. I expected them to fail later, but they still haven't come apart after years of abuse. Everyone has to go with what they are comfortable with. I have faith in my tubes and was willing to accept the possible odd leak over time. Just my opinion, but I would not force seams apart that are well bonded. I did pull hard! Gluing sections of the floor, the front of a speed tube and the majority of the transom was a pain, took a lot of time and was totally worthwhile for me. Good luck. Preperation is everything.
I've used Weaver, Polymarine and StaBond glues. Weaver is fine, but these two part glues have a shelf life of 1 year, don't like being stored in heat or cold and are hygroscopic (suck up water). So avoid old stock and previously opened cans and jars. I like NRS for Stabond because they sell a lot and it's fresh.