#embroidery hoop

I've been trying to get into goldwork embroidery and I'm having some trouble with the hoops. I've got a few different sizes of the Sullivan's embroidery hoops, but I'm not sure which one to use for a specific design. I've heard that the 4 inch hoop is good for intricate work, but I've also seen people using the 6 inch hoop for goldwork. Can someone explain the difference to me? I've been using the 4 inch hoop so far, but I'm worried that it's going to be too small for the design I want to do. I've also considered using a hoop with a tighter stitch tension, like the ones by Clover. Does anyone have any experience with those? I'd really appreciate any advice or guidance.