Everything I have read in many many forums and user reviews is that the Engl Powerball kills the 5150 on all levels - except price! ;)

If you are looking for high gain metal, the Powerball is awesome at the $2,000 price range - not cheap.

Also, the Powerball will definitely change tone/color depending on the cabinet you use so that is a factor when reading reviews.

I also found a site that lists pros/cons of the amp and some quality videos from owners here - http://www.englpowerball.com