Sub vs. three way

bob is correct, unless you put a sub in an overly resonant spot like in a corner in a small space, the sound is not directional. your directionality sounds like a function of room treatment, placement, standing waves, and yes in that set up the bass would seem 'off center'. what bob pointed out is a proven fact of accoustical science. the long room will be a benefit for the longer deep bass sound waves to develop before reflection interferes. and i also take note of statement that 2 ways are best in nearfield and 3 ways in far field. that is much too broad of a statement imo. i use 2 ways and a sub and have zero issues with directionality, fwiw, i have treated corners and walls. go for a good sub and just take your time tweaking it. good luck :3)

All of your current examples, are not quite accurate.
I have been able, to have, a sub, run by a separate amp, that
has been tweaked, to emulate a first order crossover,
while maintaining, time and phase, coherency, of the complete
speaker system!

fwiw, i have have phase time coherent 2 ways and a self powered sub x'd over at 35 hz. my speakers get full bandwidth signal and are not x'd over for sub extension. i do not get any off center sound problems. as sound from my setup from sub is so low i cannot imagine that phase and time coherency would play any role as most of that energy is felt or secondary harmonics. with tube amp the sound is seemless in this regard with two ways and their first order x-over design. my point here is that really deep bass given breathing room and good placement is not going to offer directional issues and the poster should go for the sub and not worry about buying 3 ways or any other main speakers for that matter. a sub will be fine.