I've never done a pieced afghan, but it seems to me that your gauge wouldn't matter between squares, as long as they come out to the same size so you can seam them together.
Mommy to two wonderful girls
"I don't have to conform to the vagaries of time and space, I'm a loony!" -Campbell Bain (David Tennant) 'Takin' Over the Asylum'
OTN: Cabled Sweater
, arm warmers, kids' clothes