Switching project back and forth from pro to basic

Hi, I’m thinking of getting unity pro (to remove the watermark) however the programmer on the other side of the globe is using basic. How easy is it to transfer projects back and forth from pro to basic assuming that none of the pro functions are used in the project. Thanks in advance.

It should be the same.

and watermark? I have free and there is no watermark for me.

Thanks. What I meant was the splashscreen at the start. (iPhone)