Code compatibility between 6.0.2 and 6.5

I’ve read several articles in this forum regarding 6.0.x and 6.5, their main differences and the reasons why one may choose one version or the other one.

It seems to be convenient to jump directly to 6.5 but I’ve left one last doubt that I hope someone can help me to clear.

It is known that if I save an application with a 6.0.x designer I could get some problems when executing it with a 5.x client, expecially for complex applications.

What happens if I save an application with a 6.5 designer and I try to use it with a 6.0.x client?

May I expect the same kind of problems or are the two compilers fully compatible?

TIA

Marco Zanovello