I previously had both a s5000 & a z8, personally I think both have too many potential issues and limitations now.
The s5000 or s6000 IMO were of much better build quality though the z8 has more memory and is easier to expand on.
I was happy to get rid of mine and I work itb now.
Finding parts from Akai for either is virtually impossible and if you have a problem they're both hard to fix.
My viewpoint might be frowned on but I will suggest you pass on one of the Akai relics & move forward.
2.8 Quad Intel(2008)MacPro24 gig ram,OSX10.83, DP8.04, RME FF 800,Great River ME-1NV preamp,a few microphones,NI Komplete ,UAD....assorted plugs,VI's... Vdrums (TD20 expanded) Superior2, Focal Twin 6 monitors, Shunyata PowerSnakes and Conditioners,too many hard drives... ESATA