Hi Juanito,
Thanks. I am all for simplicity, one resolution is fine, so xsession-in-backup route is OK for me. I meant to say only that I do not understand that xsession already appears to have the right parameters (resolution), which I see via cat ~/.xsession from console. Therefore it appears there is nothing to change in xsession that I can see... However it still does not work unless I go through manual setting resolution (via xsetup) during boot. This is what I fail to understand and how saving xsession in backup will help, unless overtyping xsession parameters with the same content does something mysterious to make it work...
I will need to get to the bottom of this, TCL is too precious gem not to spend time on ironing these things...