There's a file format change with this upgrade so don't plan on upgrading unless you updared both FileMaker and server to version 12 as Server 12 won't host older versions and older versions of server won't host version 12 files.
You might want to download the free 30 day trial of FileMaker 12 and give it a test drive to see if the improved features justify the added cost.
I just recently bought the 11 version of both FM Pro and Server and in the email I received it said I was withina certain time period to be able to upgrade for free. If this is the case the cost is not an issue so my main concern is time and formatting consistency. I would gladly upgrade both Server and FM Pro if it wasn't a hassle and if it didn't affect my databases so this is what I was hoping to find out. Also, if I go through with the upgrade and do not like it or if there are problems with my databases that I made on the 11 version, how easy would it be to revert back to my original 11 version? Thanks.
When you install Filemaker 12, you can use it to open your .fp7 files and it will produce converted copies of your files. There is no method for taking version 12 files and producing version 11--so this is a one way change. The conversion, however, leaves the original copies of your .fp7 files untouched so you do have the option of discarding the version 12 copies and reverting to using the .fp7 files.
If you were to use FileMaker 12 for a while, modifying data in your files and then you decided to revert, you should be able to export your data as tab, csv or merge files in order to import the data back into a clone (empty copy) of your .fp7 file.