Mike writes:

Two great cameras compared. With the Lumix G9 Mk2 now having phase detection AF these two cameras are now in the same ball park. Each has its advantage and disadvantage.
It is hard to know which one to choose, but I try and make the call.
In some situations the OM-1 had the advantage, but in others the G9 Mk2 is way out in front.

The G9II i at BHphoto, Amazon US&EU, Adorama, Fotokoch, FotoErhardt, WexUK.
OM-1 at BHphoto, Adorama, Amazon. GetOlympus. Calumet DE. Fotokoch DE. Wex UK.

PcMag tested the new OM 9-18mm II lens and concluded:

Cosmetics and branding aside, the OM System M.Zuiko Digital ED 9-18mm F4.0-5.6 II doesn’t do anything different than its predecessor. And that’s perfectly fine because focus performance remains fast and image quality holds up in terms of sharpness and flare control. The lens is missing some of the finer touches of more recent releases, however, including weather protection and on-barrel controls. Overall, the 9-18mm is an affordable, capable wide-angle lens for Micro Four Thirds photographers (even if it’s pricey compared with basic wide zooms for other systems), though we continue to recommend the M.Zuiko 8-25mm F4 Pro as our Editors’ Choice winner thanks to its more durable build and broader range of coverage.

Preorders:
OM-1II at Amazon US&CA&EU, BHphoto, Adorama, Om Digital,
FotoErhardt, Calumet, WexUK. OM Germany, OM UK, OM, Italy, OM France.
150-600mm at Amazon US&CA&EU, BHphoto, Adorama, Om Digital,
FotoErhardt, Calumet, WexUK. OM Germany, OM UK, OM, Italy, OM France.
9-18mm at Amazon US&CA&EU, BHphoto, Adorama, Om Digital,
FotoErhardt, Calumet, WexUK. OM Germany, OM UK, OM, Italy, OM France.