hi, i f i upgrade my 4.10 project to 4.11 PREVIEW when the proper final release of 4.11 arrives can i upgrade my 4.11 preveiw 3 project to final 4.11 version of engine without problem? i know its a silly question but you can never know when its about computer stuff 
Hello
You should be able to convert from a previous version of the engine to a newer version in any case. We suggest that you always keep a copy of the project prior to conversion in case issues do occur however. As you said, you can never be sure if there may be some problems that arise so it is best to be cautious and make backups.