I've been considering a 12mm Olympus for the X5 mainly because of the increased sharpness it supposedly has over the standard DJI 15mm lens. I've had a look at DXO Labs lens test database and assuming the DJI 15mm lens is based on the Panasonic there is no real difference in the sharpness between the two lenses.

https://www.dxomark.com/Lenses/Compare/Side-by-side/Olympus-MZuiko-Digital-ED-12mm-F20-on-Olympus-OM-D-E-M1-Mark-II-versus-Panasonic-Leica-DG-Summilux-15mm-F17-ASPH-on-Olympus-OM-D-E-M1-Mark-II__531_1136_1345_1136

Has anybody got any real world experience with both lenses to determine how much better the 12mm Olympus is, assuming it is?!

EDIT Just ordered a used one so I'll find out soon!

If I am not mistaken, DJI 15mm lens is OEM Panasonic Leca 15mm simulation. Can anyone confirm that. Granted DJI is charging similar price to a Leca lens.

Yes, the DJI 15mm is a re-branded Pani. And yes, the Oly 12mm beats the brakes off it.
I have had both lenses on both X5 when I had an Inspire 1 and now on X5S with Inspire 2.
Hands down a better lens.

But for a Leica read, it should not be completely beaten by an Olympic.