These rates are very accurate. In every case when looking at percentages you must use very large data samples(not one node or 10 - you need somewhere around 100 or more to get accurate data to make your conclusions, some would suggest 1000 or 10000 for better accuracy). I have my luminary botany tool already and I can assure you that the percentages are correct. When I farm 5-10 stacks of any item I am always within +- 1-5% accuracy without using any of my gp abilities. Of course If I use them things change drastically! I honestly think for leveling purposes there should be a much smaller HQ chance to make the economy work better for those that put the time in....