do you think that the two game's release structure is comparable
No, it's pretty much apples to oranges. Every game/software company can pretty much plan their beta and release schedule however they want. A stress test or beta event on date X doesn't mean a release must follow Y amount of time later.
I've heard the date of 6/26/12 thrown out there alot. Not only because of the Jersey conspiracy, but that date has also come from the mouth of local Gamestop employees as the street date. That could just be total nonsense, however, it does fit in with well considering the aforementioned. Thoughts?
Well... that's the date currently in GameStop's system. You can search up GW2 on their website and see it. However, it has been said that retailers sometimes put in place-holder dates for various reasons. No date is reliable until ArenaNet makes an announcement about it.