I've been humming and hawing over what to do with my 2013 990A's icky 210mm WP's... The obvious cheap route is to have them sprung and live with short travel, but I've already dent a rim and am slowly wearing off the inside of my high front fender due to bottoming out hard all the time. Next options are to send to SPS and have it jacked to 265mm 'S' which is viable and common and known to be a great upgrade. Depending on price comparison (obviously yes, these O's will be more $$$, but substantially better for off road which is what I ride 80% of the time) these are now on my short list to ponder for suspension upgrades.
I'm no Dakar racer so 300-320mm is just too much for my needs. 277mm sounds more reasonable and more manageable for my less-than-pro-skills. If I'm in I'd be in front and rear also as I don't believe in mix-matching suspension parts. I'll keep following for a price line and more details. Cheers!