I can attest to the fact that... no matter WHAT you do with tips... they WILL eventually come off. It's not a question of "if", only "when".
A lot of the "elitist" saber folks have disagreed with me for years and years... but the proof is in the pudding. The amount of sheer usage that most of my sabers have gone through is enough for me to say this with impunity and certainty, lol.
The reason they fly off isn't how "much" or "little' glue that was used--nor what type. It's a PHYSICS thing. I won't go into the details, but as you guys probably know, the poly-tubes actually FLEX / bend / give during a strike. Sure, you can't SEE that without some super slow-mo + 2000fps cam or whatever... but these things DO bend/flex. It is actually why they are so "strong". Supple like bamboo, strong like steel.
So it's a pressure thing. The tip wants to fly off simply because the warping of the blade causes the blade to loosen around the tip. There is very little that can be done about this, short of having some REALLY crazily designed tips made--which is not cost-worthy... it's far too expensive for such a minor concern. Believe me, I tried some stuff back in 2007...

My only suggestions:
* Buy a handful of extra tips. Not a big deal.
* In addition to whatever glue was used for a blade (whether you made it, or you bought from Ultra)... add a thin layer of a "gummy" type of glue all around the seam on the outside
* Wrap a thin layer of packing tape (clear) around the tip and blade. Try to keep it as clean as possible, and you know... make it look nice.
These things have helped me greatly. By the way, in a pinch--if a tip DOES fly off, you can quickly "short term repair" it with the packing tape if you have extra tips (or found the lost tip).
Some people have chosen NOT to use tips, and "plug" the blade with some kind of rubber thingy or 2-part epoxy or whatever (and then sand/round off the edges)... but I personally think that is pretty silly, as...
BLADE TIPS *DO* LAST A VERY LONG TIME!!

So don't worry too much, unless you thwack & whack your sabers around 6 days a week for hours each day...
Good luck with them, and although we de-railed the thread a bit here... it's a good concern to bring up. Those tips CAN be a pain. But I'm just telling you guys... there is NO blade out there where the tip will stay on "forever", or... there's no way to say blade X's tip is really "better" than another's, for the most part.