I can report that the Panasonic Lumix 25mm f1.7 lens does work with the DJI X5. Has a pretty fast autofocus (for the X5) and seems to lock in pretty well. Haven't had a chance to really push it yet to see what it can do, but for less than $150.00 bucks (on Ebay) it was hard to pass up...
Be careful when ordering this, I placed an order from this guy off his ebay site before Christmas and am still waiting to receive a shipping number. I filed a case with Ebay today for a refund and waiting to hear back from them.