We ran a 336 years ago and then went to a 348.  It was a big improvement.  We had several 348's and then upgraded to a NH 575 about 10 years ago.  It was a big improvement.  We currently have a NH 5070 which is the same size as the 575 with a few improvements (moved the star wheel back farther which makes the bales more consistant.  Also changed the location of the pickup drive belt to make it easier to change.).  I would not go back to a JD (the last 348 we owned was the biggest lemon due to VERY poor quality control at the factory).