If you send your UFT stuff to FTM via gedcom, you will no doubt lose some information. It only takes the basic events. Your best bet would be to get The Master Genealogist program (www.whollygenes.com), which takes UFT information directly into the program without need for gedcom.
Not sure what you mean by "losing space" in the program. Unless you have an enormous database. If that is the case, you might want to split" your projects to allow you more space. Ultimate Family Tree needs approximately 2.5 MB free disk space for every 1000 individuals in a project. If you are getting an error note of some sort, let me know what that might be. You may need to use some of the project utility features to check/compact your files.