Released this morning SLRGEAR's review says - "the (Olympus) 300mm ƒ/4 is thoroughly impressive on all fronts: excellent sharpness and all-around wonderful optical qualities with little to no distortion, aberrations or vignetting. What's even more impressive is the lens' stunning image stabilization. Combining lens-based and body-based I.S., the Olympus 300mm ƒ/4 Pro lets you capture handheld images down to shockingly slow shutter speeds. All this, plus impressive close-focusing capabilities, make the Olympus 300mm ƒ/4 Pro a stunning lens for the professional and advanced photographer looking for a top-notch wildlife, sports, stage performance and close-up lens no matter the weather or lighting conditions".
Bugger - I'd convinced myself I didn't need it
(If anyone in UK is rushing to buy it consider Amazon.de as the euro price is roughly £200 less than the UK price and no import tax from Europe).