I'm new to jets myself and in the process of building the Hawk as well.

The 100 doesn't use THAT much more fuel than the 85 per minute, but again, not much room for error with a jet and running out of fuel. I suggest you run your jet on a test stand and watch the fuel consumption yourself. It might make you change your mind. Jets really suck down fuel at an almost alarming rate. My K85 on the test stand sucked up 12 oz of fuel in 160 seconds...

Just err on the side of caution your first couple flights and see where you are at...

2L = 67.6 oz

At 12 oz / 120 sec, I figure 11 minutes of fuel. But without risking running out of fuel, I expect to be at 7 minute flight maximum with the K85.