Can't speak from personal experience, but here's a repost from NASIOC:
taken from the
www.xt6.net FAQ....
Q - My power steering works sporadically or is out entirely; I've heard the XT6 uses some sort of special power steering motor and fluid - how hard is it to repair or replace?
A - The XT6 uses a unique electrohydraulic system of providing power assist to the rack and pinion steering system. Subaru dubbed it Cybrid steering (whatever that was supposed to mean) and it is very precise and reliable. Making use of an optical sensor "watching" the movement of the steering wheel coupled with some electronic brainery under the hood the Cybrid system uses an electric motor to power a hydraulic ram system to pump the fluid where it's needed. With this system there is no belt driven power steering pump like that appearing on almost all other cars. The motor is highly reliable and generally performs flawlessly. However, recently a spate of owners have had problems with the electric motor's brushes wearing down to the point that they need to be replaced and this causes hesitation or it causes the unit to not function at all. Replacing the brushes is not too terribly difficult, and the brushes themselves are very inexpensive if you know the right place to get them (try Anthony's Subaru in Kelowna, BC - ask for Paul). Of particular note is the fact that there was a recall on the power steering motor to install a wire to correct similar sporadic operation... if your power steering motor has a long (usually blue) wire running from it to a wiring harness in front of the driver's side of the firewall, then you have had the recall done. If not, this may be the source of your hesitation troubles.
One last word on the XT6's power steering system: UNDER NO CIRCUMSTANCES - REPEAT - NEVER EVER use "regular" power steering fluid in the XT6's system. It WILL ruin it - period. The Cybrid power steering fluid (Subaru part # K0209A0080), although far more expensive (about $25US for a quart/liter) is the ONLY fluid that should ever be used. It apparently is so dramatically different in its chemical make-up that use of regular fluid will cause rubber O rings to deteriorate leading to pump failure, etc. Twenty five bucks is far less expensive than a new power steering system. If you take your car to a commercial establishment to have your oil and other fluids changed, it is advisable to instruct the technician not to touch the power steering fluid. You may even want to print a clear warning on a bright orange label affixed to the unit - it may sound extreme, but it's a small thing compared to the costly repairs and frustration it might avoid.