Can I use Aperture in the new EL Capitan Operating System?

Aperture 3.6 is running on El Capitan. However there have been a few minor glitches reported, for example, that OnScreen Proofing can cause overexposed, washed out images. Others have reported, that Aperture is very slow on startup. For me it is working well.

Yes. I must have on screen proofing unselected. PITA.