I have a choice between a new Mackie Control Universal Pro* at EUR 1,200 or a used Mackie Universal Controller eMagic** for EUR 400. Naturally, the used one seems more attractive (price!) but can anyone advise if it will integrate as well with Sonar 8.5 as the newer model will?

Many thanks for advice!

* Mackie Control Universal Pro Expandable DAW Controller
** Mackie Universal Controller Usb For Sale in Galway from travelman

I would consider the mechanical parts like the motorized faders.  See if parts are available.  I bought a used MCU Pro and the seller had a few new faders included in the deal so I know that I have those particular parts covered.

Mod Bod hit the nail on the head. I have the older MCU and extenders that use the old style Penny & Giles faders. I have one that is starting to stick on the extender and does not always want to calibrate unless I give it a little movement prior to turning on.
 
They don't make those faders any longer and about my only choice would be to find an old unit for sale (CHEAP) and use it for parts. I have opened the unit and cleaned it well but it seems like it may be the little string that the motor drives the fader with. It looks very delicate and I really don't want to mess with something I don't understand.
 
If things get worse I will probably just sell my units for parts and purchase new Mackie Pro's from Sweetwater so I get a 2 year warranty.