You may very easily find out if the transfer is to your satisifaction. When you transfer to TMG vai the GENBRIDGE process you do not lose the data that is in the UFT format. It creates a completely new dataset int the TMG format and does not change the UFT data in any way.
If you do not like the transfer, you may do it again and agian until you get all of the transfer options set to you own satisifaction.
There is no harm in trying the transfer. By the way, there are a few minor glitches in the 4.0a program (which all programs have) which in no way can harm the UFT data. There is a new release of TMG which should be available shortly (sometime this week I hope) which addresses these problems and will be available for free from http://www.whollygenes.com/http://www.whollygenes.com/ site.