No problems. You will just need to download the drivers for it.
Driver Downloads and Updates for Pro Tools and Standalone
As far as the Eleven Rack Expansion Pack (ERXP), I do not think Avid will transfer it, but there is no need to transfer it anyway. Once the ERXP is installed on the 11R (Firmware 2.0.1) if never needs to be run again.
If you need to run the first section of the ERXP in order to get the updated UI files for the Eleven Rack Editor window in PT, its still not a problem, you can download the ERXP here.
http://avid.custkb.com/avid/app/self...p?DocId=425171
Make sure you get a good deal on a used unit. I would not pay over $500 for a used one personally, unless it came with PT9 or PT10 license.
Another thing to be on the look out for is to make sure the seller can confirm that the 11R does not suffer from the sample rate problem that some of the older units had.
It may be best for you to buy a new Eleven Rack that includes a warranty, a new v.2 iLok, PT9 with free crossgrade to PT10, and the ERXP. Normal price is $899, but many stores have sales going on, perhaps not specifically for the 11R, but a general 15% off or a certain amount off depending on how much you spend ect.... And the holiday season is coming and Music store always put out rebates and coupons this time of year.
Then there is eBay, where some ebay stores are selling the 11R with PT10 and the ERXP new, from $699 to $799. Some are buy it now only, some have a Best Offer option.
Just make sure on whatever you decided, to do your due diligence before buying, and get all the specifics in writing from the product page text or from an email from the seller, maybe even go as far as to print out the email or product page text. Use a Credit Card or Paypal so you have recourse if the product is not what was promised.
Good luck.