I've have had GTL cells when they have been bundled free with lights that I've bought. They truly are dire. The capacity claims are always fantastically over the top. I've kept them as spares for emergencies but never use them routinely because I do not trust them.
You are totally right that Boaz has no personal experience of these cells, however, like all of us, his opinion is informed by what other trusted BLF'ers have reported. Unanimously the view of GTL is very, very poor indeed.
After all would you trust a company that claimed this.