I wondered that for years, and after hearing various conflicting things on the internet, finally got a straight answer once I started volunteering out there. Here it is:
Yes, the 2000s have operated at IRM before. I think it was around the year 2000 or so, but they made maybe four mainline trips. Since they don't have trolley poles, they were jumpered to a pair of 6000s (6655-6656). The 2000s pulled the 6000s one way down the mainline, and the 6000s pulled the 2000s the other way. I don't believe these were "public" trips and when one of the 2000s developed a motor fault (likely resulting from deteriorated insulation in one of the motors) it was decided to simply leave them be until they could be put into indoor storage, where weather-related deterioration is a non-issue. The cars themselves have more than half of their indoor storage space paid for (from last year's Snowflake Special and general donations), and if that remaining amount is covered before the next IRM barn goes up, they will be placed in it.
That old car might be worth money!