If I've read the glossy brochure correctly, your recently acquired MQ-9 Reaper has a SAR, or does it?
Are you seriously comparing the dinky little Lynx SAR on Reaper with the ASARS-2 on Sentinel?
Just because both say SAR on the box doesn't give the same capability.
That's like saying that we don't need the E-3Ds capability because the Dominies have a weather radar in the nose so we'll just use that instead - after all they are both radars.
Without giving anything away on the differences, it is worth noting that Lynx SAR is the size of your PC tower and the ASARS-2 is the size of your car.