Jones, I have seen 3 Soldiers go AGR (Active Guard Reserve) one worked for UPS for two years then went AGR (14 years prior service), after his five Active duty years were up the company called him and he declined to go back, UPS just dropped him from their books.
As for the other two, one was offered his job after being gone 9 years the other 7 years. So the bottom line is after the 5 year federal USERRA law and if your state Department of Justice does not have any additional time the Service member can be off after the 5 year period it falls on his/her employer if their company wants to bring him/her back.
On my very first Guard deployment during the Gulf War and my first deployment for OIF, UPS continued to pay for my medical benefits and paid me the difference in my pay and called my wife every quarter to make sure she was doing okay. They don't do that anymore but what they did was greatly appreciated and it showed me my company was also making sacrifices.