Use of legacy models vs new construction

Legacy:

• confidence: object has been used over an extended period, and (hopefully) also verified correspondingly.
• documentation: usually aimed at use and not so much at contents in terms of how things are done. Latter is often considered proprietary knowledge and consequently hidden from the user.
  Consequence: often little is known of what is actually happening inside — remains with the creator.
• outdated: generic ageing effects of required utilities such as hardware and software
• design limitations: available technology imposes constraints and re-orients objectives to make it work instead of achieving the original goal

New construction:

• fresh view: new can be fresh but does not need to ignore old. Knowledge integration hopefully improves overall.
• new implementation: enables the use of new tools, has thus the potential benefit of other discipline’s improved knowledge integration.
• redo:
  • Can imply more work and thus increased investment
  • Construction process is likely to introduce errors
  • Old errors may surface and can be corrected
  • Better chance to aim at original goal