I traded my 06 K12S last year with near 90k miles on it, original owner.
It did not have ESA, I took what they had on the floor in detroit at the time.
The stock shocks started beating me up around 20k miles.
I had Ohlins installed at the dealer on the K12S (ordered them to my weight) at about 24k miles during the service, pricy! about 2800 bucks. But, they are re-buildable, unlike (supposedly) the BMW stock shocks. I would never rebuild a stock shock anyways, I ride like a fool sometimes and need all the help I can get.
The rear Ohlins had the knob-adjuster, I would reach down and turn it while riding if needed (a bit scary). I never adjusted the front Ohlins once installed, no need to do so.
Fast forward to my 2011 K1300S, about 29k miles on it with ESA. I'm already feeling the sponge where it used to be more firm
I really like it for my style of riding though and use it quite a bit, I don't think I'd go back. Note that I didn't own a car for 6 yrs, only the bikes so take that into account.
What I can say about the Ohlins on the K12S is, they seem to last forever compared to stock shocks. And..they are rebuildable, I had this done on my 02 K12LTC (RIP) when they (ohlins) had over 80k miles on them, the rear was starting to pound me a bit.
On the K12S with the Ohlins, they were still going strong when I traded it in, thats about 60K+ miles on them!! Might be worth the change to put some in oneday on that 05.
And the 06 was running stronger and smoother all the time, it just kept improving! of course I kept up with all repairs and maintenance since I rode daily.