Lesley, in an attempt to answer my own question about different flavour profiles of syrup made over wood vs. propane I conducted a major experiment yesterday. From the same storage buckets I split the sap, with half going to wood fired and half to propane fired. The nearup is very close to syrup now and I'll be able to offer up my thoughts on any differences very soon. My sample size was something upwards of 75L+ being directed to each cooking method.