if you're interested in an adjustable unit (and the one on your bike isn't adjustable), get your hands on a take-off from a 748/916/996/998... almost exactly the same length and they're available dirt-cheap on eBay and used parts classifieds. whatever material the TPO part's made of, i couldn't imagine blowing that much cake on it.
From my eyeball assessment of the rocker & linkage, as you shorten the tierod or lengthen the shock, the suspension will become more progressive.
If you have an adjustable tierod and an adjustable length shock, you can alter the progressivity while maintaining the same ride height. Or alter the ride height while maintaining the same progressivity.
Whether you can notice any difference on the street, that's the question.
With the Ohlins parts front and rear, you're in excellent shape already.