unfortunately you will not get a concensus from this forum on softening boots. some guys out here get it, and some do not.
i believe that there is no benefit from removing 1 bolt. this raises the question as to why you would do it. the only functional benefit is the psychology of the placebo effect.
secondly for any overlap shell to properly function, the lower shell and the upper cuff must be connected at the spine. the way these 2 parts function is what an overlap ski boot is intended to be. no connection, no rebound. no connection and you may as well dust off your old Salomon SX90 Equipes with your K2 VO slaloms and throw your hips left and right to turn em.
to soften a boot you can increase the depth of the saddle cuts, you can but a "V" or "U" cut in the spine, you can increase the arc of the lower cuff strap to increase the ROM and get the cuff strap off the instep of the lower shell.