I will not go into a whole discussion about which there are hundreds of tshuvos over here. If you want to base what you do on am haaratzus do so at your own risk. Do you know anything about how to find a treifo in the dakin or in the veshet to know whether they are of the same complexity or not? Why are you assuming that they are the same? That is like saying that since a doctor is reliable for surgery on an ingrown toenail he should be reliable for brain surgery too.
I base what I do not on svaros but rather in the fact that IMO they are a good hechsher and they are telling me it's kosher. The fact that they, and most European kashrus agencies, never took on the chumrah of glatt doesn't change that. As an American, where glatt is the way of life, to the point that not glatt in America means not kosher, I personally would never eat not glatt meat. But poultry is different.