I have used green pecan with pretty good luck, but I've only done that twice. You need to start with a good bed of coals then add a seasoned split every now and then to keep up the coal bed.
This was in my stickburner, I don't think I'd try it as wood chunks in a charcoal smoker. Try it and see what you think. Use either a cheap piece of meat (whole chicken) or an empty cooker to gauge the smell and test it out.
A local restaurant here uses green hickory and pecan from the same source I got my wood from and their food is amazing. They use it for grilling and the aroma and flavor are outstanding.
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