I'm pretty sure I know the answer to this but will a 1098s Ohlins just fit straight into a 848 Evo? Are the sprung the same? There are loads listed on eBay for 1098 but only ever a few for the 848 evo.
From chats I've had with Ducati Glasgow, the ride height differs between the 848 and the big bikes. Not sure if this is affected by changing over the shock but you might want to investigate that. Even if it doesn't change the height, it looks enough of a difference with the bikes side by side that the shock might need setting up to get it working properly.
Yeah, I would get the Shock serviced and sprung for my weight, but tbh I think I might just get a static set up on mine first because actually the Showa shock isn't too bad on the road. Will have a chat with my local setup guys and see what they reckon as it's pointless spending on a shock that may/may not be a step forward.