I agree doing it from scratch to 2017 is the best and clean approach.

I am currently doing the upgrade process in a test environment, and later will do it on production.
Our production server is a very robust physical server, test environment is a VM.

We want to reuse the physical server and we don't have another good physical server available to do this at this time.
So in the case we chose in-place upgrade. 

That is  the reason I posted the questions.

Thanks.