Hi,
The problem with this question is :
- Sharepoint technology already provide the solution for this issue : Alternate access mapping
- if you configure it on Sharepoint, there is no server performance impact, no rewriting issues, the solution is supported by microsoft
- if you do it with F5, you have to search in every response page for internal url (encoded in multiple formats, some colons are Unicode encoded), 90% bigip performance impact (i have a customer where a bigip felt down to 10% of concurrent requests per second capabilities by enabling response data)