i am in no doubt that the showa front and rear combo are a far better deal then the Marzocchi/Sachs combo.. and a very fine alternative for the more track oriented Ohlinses... and even on the track they will stand their ground..
The 899 has a Sachs rear shock, just like the 1199 standard model, but the one on the 899 is cheaper. It lacks the ride height adjuster that the 1199 Sachs rear has, and overall if you look at them side by side the 899 one just looks "cheaper". I'm putting a revalved 1199 Sachs shock on my 899, mainly so I can get the ride height adjuster for tuning at the track.
Would very much like to hear details about your revalving of the Sachs. Could be a viable alternative to going all-in on an Ohlins/Penske/Whatever replacement.