I'll go further with this thought process... if your sugar levels are high, the amount of plant material is going to be higher too, making this particular thought from Nitro seem irrelevant to me based on my experience (ie: if you were even smoking the sap, which you are but not so much, it would be balanced out by a higher % of plant material). I'm aware straight sugar doesn't burn that well, and also that weed burns better after curing, but my end product is excellent off the plant and I keep my brix levels as high as possible. You are just measuring the sap, which you don't actually smoke.
Stuff I've had that burns awfully was fed improperly. Whether this is from nutrients hanging around in the plant unused (the plant can store some) or excess chlorophyll or what, I don't know. At least this is my experience. Curing can solve a lot of issues granted.