MIJ vs MIT for Boss pedals only matter for a select few pedals.
Matter = if you are concerned with how it affects your playing, whether in the bedroom or live.
The old choruses are something. The old, silver screw DS-1 is something. The MIJ DD-2/3 are something.
They say ignorance is bliss, if you play with your MIT gear and you are pleased, sure, carry on, but if you ever get the chance to play them side by side, an MIJ and MIT, do it. You never know if you are missing out on something that would make your practice time sweeter (which in turn, affects live performance no?) or if... its just hype.