Hi Kiwiguy,
No one is ever "just" a PPL - not in my book anyway. It still puts you ahead (or above) 99.8% of the world's population.
On the subject of burns, there is nothing "econ" about your quoted burn of 4,440kgs per hour for a -17 powered B737. That's almost into B767 territory, and well above B757. I'd guess the right figure for a -17 is around 2,550 kgs/hour for 3 hour sectors (quite long, admittedly), and I'd expect -9 to be close to that.
As for -9 vs -9A, the later "A"s (-15A and -17A) had minor gas path improvements and therefore slightly better SFC, as I recall.