Bio Balls: Yeah or Neah

[Captainhemo]

My tank (60 gal + 50-60 lbs LR, 20 gal sump) has been up for about 3 years. The first chamber of my sump has always been full of bio balls but I am trying to make room for a new in-sump skimmer, currently have a hang on back.
Can I lose the bio balls and if so, shoould I remove them slowly or all at once ? I've also always run a couple of foam Fluval blocks in the sump, should I also consider removing these once I upgrade my skimmer ?
Is it generally thought that this type of wet/dry and mechanical filtration does more harm than good ?