You can't ask directly here, and we are 1st timers ourselves anyway, but on the line we travel frequently, we are able to compose a few questions for others that they can use to screen for an agency that is particularly knowledgeable about that line. Only those closest to a particular line are, for example, able to accurately and without research answer certain kinds of questions about shipboard specifics re anomolous cabin layouts, procedures, etc.
I'll bet there are SS veterans here who could compile a short list that might reveal this.