Well, AlexG, that is certainly a fair question. I am sincerely flattered that you took the time to ask me. 🙂
The answer may be as simple as the fact that I am not truly a member of the FMG or GTS genre in the eyes of many.
As you know, some see the genre as a club from which those that are not true believers should be shunned or criticized or expelled.
I’ve actually been "scolded" many times over the years for not being true to either genre. As a point of information, I’ve also been criticized by many in the BE community because I tend to lose interest there too if breast size becomes ridiculously large. An example with which you are familiar — I enjoy giantess.com but I tend to keep a low profile there. I’ve stopped posting art and stories there because I was criticized a bit too harshly too many times. I’ll never understand people who go out of their way to criticize the creators of things that are essentially "free".
The less simple answer to your question is that — it depends. I do not have a predetermined, quanitative, cut-off in mind when I look at a picture or read a story. It depends on what the artist or writer does or doesn’t do with the characters that primarily determines if and where the point is at which I lose interest.
I’m sure that you have read a story, for example, where the plot is barely an aside to graphic descriptions of sex or stomping or swallowing or pummeling. That is fine if that is your primary interest, but it is not mine. A well written story, with decent character development can hold my attention almost regardless of the relative sizes and strengths and other characteristics of the characters.
The exception is graphic violence. This is where most authors immediately lose my interest. However, I do not intend to sound critical. A lack of interest for something on my part is not meant to be criticism: to each his own. I do not wish to be injured or killed. I do not want to see others injured or killed. I do not want to read about others being injured or killed. I do not want to see or read about senseless destruction. My experience with the GTS and FMG genres is that most stories and pictures that feature women over 20-feet-or-so tall or women who are able to toss a car, invariably cause mayhem, injury, and death: accidentally or purposefully. In the hands of many authors, those characters are usually simply too big or too strong to interact with others without causing problems. And, IMHO, if they are not interacting with others, then there is really no story anyway. I suppose you could say that it is at that point that I would consider a given author’s character to be "ridiculously large or powerful".
Having said all of that, I do hasten to mention that I appreciate many of your works!
Tschuss!
Hunter