I don't think I've read about anyone in the Legacy crowd upgrading to the Cobb cams. There are a number of Impreza owners with them - try searching the N/A Powertrain Forum for some discussion.
I'm seriously considering them myself - that extra power throughout the rev range is very enticing. I should (cross your fingers) have an MRT exhaust in the near future. That exhaust was dyno'd at about a 14hp gain, add an intake and cams and I should be +25hp I would think.
'97 Legacy 2.5GT sedan