I put Tophat collars on GT Traditional XT's and like them for both hunting and 3D. The Traditional Classic XT's are a fair bit heavier and micro-diameter and come with the ballistic collar. They might make a fine hunting arrow but are very heavy for 3D.
I shoot GT Pierces (.166 ID) and Kinetics (.204 ID) with their supplied inserts and Ballistic Collars. They're not completely bombproof but pretty dang good. Helps add FOC too. I don't see where the Traditional XT (.246 ID) has Ballistic Collars. The smaller diameter Classic XTs noted above do.
I have used some of the arrow systems mentioned and agree they are fine.
As an alternative you might consider using pieces of aluminum arrow shaft to reinforce the GT trad shafts you have been using. A couple inches of aluminum glued over the end of the arrow shaft behind the tip with a half inch glued on the nock end make for a pretty burly arrow in my experience.
My mistake, it is the Classic XT and by the website description, the regular GT Classics take them too. Weights appear the same between the Classic and Classic XT so I am not sure if the XTs are just more expensive for the fake footing or what? I have a dozen Easton Bloodlines I received in trade that I am using right now. Not too bad. I would like to collar them but may just use old aluminum shafts as recommended and keep shooting my tried and true GT Traditionals.