Thank you for your post.
The functionality is not going to be identical. For one, if you have any field validation, this won't be executed until the record is submitted. You won't have the same menu items because you are now running a browser that has its own menu selections.
Yes, Instant Web Publishing has several limitations, and Custom Web Publishing either with PHP or XML/XSLT allows you to go beyond those limitations.
If you have FileMaker Server 11 Advanced already, then please review the "Custom Web Publishing with PHP" guide that comes with the product. If you don't yet have the product, you can view this manual online at: