I think it\'s good idea to send letters. It can expedite the process.
Right now I-485 is the bottle-neck in the whole GC processing in TSC -- It takes about 2 years to process, but other centers take only about 6 months -- what a defference -- one year and half! It\'s unfaire! We paid the same tax, sir.
Note: it\'s TSC that send the visa approval letter of the terriorists to the school 6 months after 9/11 attack! There must be something wrong or problems at TSC.
Now I-140 is pretty fast, and they flood to I-485 stage. Thus more I-485s are waiting.
So why not send letters to INS or Congressman to express your concerns, especially your case is long time delayed?