Pros:

• Your system (presumably) already works just how you want it to. In other words, if it isn't broken, don't fix it.
• You can wait until all of the bugs are worked out of v9 before migrating to it.
• There is no direct, obvious cost involved in staying put.
• You can avoid the time and hassle of working on your current application.

Cons:

• You cannot take advantage of the plethora of new features of the FileMaker 9 product line.
• Your system will not be directly compatible with any new systems you build with v9.
• You will soon be prohibited from buying more seats of your current FileMaker version, if you aren't already.
• Your operating system may stop supporting the version of FileMaker you currently use.
• Over time, fewer and fewer developers will be able to help support your application.

Pros:

• You can take advantage of most of the new features of the FileMaker 9 product line.
• Your system will generally be directly compatible with any brand new systems you build with v9.
• Many developers will be able to help support your application.
• It is possible to migrate to v9 on a module by module basis, allowing you to spread the cost, labor and potential SNAFUs of migration out over time.

Cons:

• While converting existing database files to v9 is possible, it is a tricky business. Your solution will have to be carefully analyzed and possibly even partially reprogrammed before conversion to v9 in order to ensure that your system will work properly in v9. After conversion, your developer will again have to comb through your code and test every feature to make sure your solution works properly. There are literally 100s of pages of caveats and warnings regarding converting an existing pre-v9 solution to v9.
• You will only "sort of" be able to take advantage of the new relational capabilities and security features of v9.
• You may still be forced to use much redundancy and bloat in your relational structure that is simply not required in a fresh, "from scratch"-built solution in v9.
• You could spend an awful lot of time debugging.
• You will always be tied to a system built using the pre-v9 multi-file approach as opposed to the dynamic, rapidly-developable one-file/multiple-table approach used in v9.
• Your solution won't be as ODBC or Web-friendly as it could be.
• You must make a significant monetary and time commitment to such a project.
• Many developers might not be interested in performing such a careful, delicate operation on a pre-v9 system.
• There is a slight learning curve to using v9's new features, but the pros of having the new features outweigh the time it will take to learn about them.

Pros:

• You can take full advantage of all new features of the FileMaker 9 product line.
• Your system will be completely and directly compatible with any other brand new systems you build with v9.
• Many developers will be able to help support your application.
• Your system will be fully ODBC/JDBC compatible.
• Your entire database system can be shared via the Web after literally one click of the mouse.

Cons:

• You must make a significant monetary and time commitment to such a project.
• There is a slight learning curve to using v9's new features, but the pros of having the new features outweigh the time it will take to learn about them.