If you stick a J and H flying next to each other, the J will ALWAYS be more fuel effecient. For starters your 300KTAS you fly at is pretty much our long range cruise. If we are at 320KTAS it's still more effecient.
Besides, a J at 26-28,000 (temp dependent) fully loaded will ALWAYS be more effecient, and faster (and can get above a lot of the weather) than the full loaded H/K sitting at 18-22K
Quite possibly, but there isn't very much in it. Your H's may use a lower TIT for cruise than we do - I think we're pretty much the only nation left putting 985 deg through the turbine in the cruise. Our normal HSC TAS is around 310-320 in the low 20s, with an average load and AUW.
Not RVSM compliant yet.. The aircraft meets the certification requirement but no-one wants to pay for the paperwork.
Now THERE'S a surprise. However good EITHER aircraft is, we are BOTH held back by a chronic lack of funding.
16B