Question
You have already stated it is middle of the road BTU for indoor woodstoves. Do we have a high creosote level when burning this type of wood? Right now we have maple and oak in our woodpile but can resupply next spring from a local sawmill which is close by

Answer
Hemlock gives off relative low heat, throws off many sparks when burned, is generally rated for firewood as fair, has good aroma when burned relative low heat produced 15.9 Thousand BTUs per cord of wood (oak which is one of the prime woods has 30 MM BTU's per cord). It is similar to pine.  Overall it is a fair wood for firewood.
Creosote is more in conifers than hardwoods but the main problem comes with burning green wood. When seasoned hemlock should not be a problem. I could not find exact creosote levels but just general differences in conifers and hardwood.