I'm sorry, I don't know why but I thought it was an ID thread. My apologies for assuming and not reading well enough to realize you where sharing and providing your personal experience.
Aggression wise I haven't really seen any except for as I said squabbles over hides and I hear it more than I see it as they grunt very audibly, otherwise I wouldn't be able to tell as no one is ever injured. Again except my female Trachy who does receive a decent beating if she can't get away from the male quick enough when he is feeling amorous. Mine have bitten me on occasion but it's my fault as I handfeed them so they do at times get disturbed while I am cleaning and assume it's feeding time and after some exploratory nudges will at times take a investigative nibble. While I find Gulpers to not be aggressive I do find them to be more likely to bite me. In all instances between the two species I find it to be a predatory response rather than aggression. But I've only had 4 Trachys and 4 Gulpers so I definitely can not speak in definitives but just share my personal experiences.
The Trachys are as you also mentioned way less "clumsy" and more "determined" "aggressive"? in their movements than Gulpers. Sorry hard for me to find an appropriate description. They are capable of quick movements and employ them in their search for morsels. They are like mini bulldozers ime, pushing and headbutting away potential competition for food. Mine also hide most of the time only coming out on occasion to patrol for food or when food is introduced. I have a very, very large pipe ornament which is my males preferred hide. He squeezes in with a 12 inch Maroni, !2 inch Serratus and 10 inch Rhinodoras. They are one of my most daring cats as they have absolutely no issue with eating from the surface or my hand with the lights on.
I haven't taken a video of them in awhile since my DSLR broke but I'll see if I can get one of them feeding. Mine are I believe are maybe 14 inches. They grew fast to about 8-10 inches but slowed after that for me.
Edit: By the way I loved watching your Gulper eat off your Gobies head. lol ?
