After a preview of the MD-82, 83 and 88 with PBR, FlytheMaddogX developers have posted a nice update regarding the development of the new MD-83 and 88
Developers of the new MD-83 and MD-88 have already confirmed that these aircraft have entered beta, but are also finalizing the ‘advanced icing’ feature that will be included in the MD-82, 83 and 88 upon release. They have stated in the forum post that they are indeed using the default P3D dynamic reflections set between off and ultra. With the dynamic reflections set to off, and no PBR, you will see the best performance. However, with PBR active, and reflections set to ultra, performance will decrease. So its a quality over performance situation.
With the previews posted above, these are the in-game settings that the FlytheMaddogX developers used for said testing. The specs and add-ons used during these tests are your typical add-ons that the vast majority of sim users use daily. So this puts it into perspective on the kind of performance you could expect.