I like your idea of doing some test mini's to check it out and see how you like it. I'm wondering if the teachers you are talking about are against using a cotton thread because the wt. of the thread is lower (thicker) usually on cotton than on some of the poly's or silk. (most of them are #50-100 wt) and with a whole cloth it seems that most are pretty densely quilted to get the awesome designs in them. Seems like many whole clothes are made with a #50wt for the main design, then something even thinner, like Bottomline, for the filler design. Also, you say you like the shininess of the poly's like trilobal, but cotton is never shiny. If you want a non-shiny poly, check out SoFine or Permacore--both are nice, matte, thinner threads that would probably work fine (and SoFine is available in both #40 and #50 wt--more colors in50). They both look like a finer cotton finish.