Tyron,
Are you referring to upgrading the pump on the BH90 skimmer or purchasing a new Classic 110EXT skimmer?
They are two different skimmers so it is hard to compare them. External, Internal or Sump Saver skimmers are more efficient than HOB skimmers. If you are going from an HOB skimmer to an External Recirculating skimmers, that in itself would be a huge upgrade.