The only reason I can surmise for doing F15 landings is fuel economy and perhaps noise, but the latter is debatable. I thought there were already operators certified for F25 normal landings. F15 must be considered a non-normal as you need to select flap inhibit on the EGPWS.
You say your "operator finally authorised..........." I wonder what the discussion was between Boeing, FAA inspector & operator. I would have expected great scepticism from the former 2 under economic pressure from the latter. This will be until the first overrun or set of burst tyres.
Is there a minimum runway length that is stipulated for this? And I assume no braking issues or tailwind. I can imagine some interesting flight deck debates from a disagreeing pilot. CRM could be tested.