Is there any reason to believe DOJ attorneys make any more than other attorneys in the federal government?
I'd doubt it-there are websites you can check, but my bet is that the staff counsel for House/Senate committees probably make more and/or get better benefits. I think I saw somewhere that the average salary for committee counsel was around $80-90 a year plus bonuses, and they may also get split salaries-some may come from a member's office. Senior staff on the Hill get treated pretty well, from what I've seen.
Of course, they also have much less job security than the average DOJ attorney.