Shy Torque,
You guessed quite right that my experience of of dead-side joins is zero. Actually the procedure was unknown to me, never mentioned in my training, and I only came to have an idea of it - probably inexact - through perusing these pages.
Actually I am one of those who should - according to some - subscribe with "inexperienced beginner pilot".
So I can consider the differences theoretically, even so my doubts remain:
-) the overhead join is done ABOVE circuit altitude, allowing a wider field of sight than the deadside join, which I understand to be done AT circuit altitude
-) overhead joins are done from a 360° "origin", spreading the risk of collision over a wider area. The deadside join can only be done from a 180° field limited by the extended runway axis. Whether this is a pro or con can be discussed.
Also, I fail to see the relevance of the blind spot under one's plane. It does exist, for sure, but why should it be any more dangerous at some phases of flight than at others?
Thank you for discussing patiently - I am learning again!