I had the same problem, the other Sqns knew the score and transferees kept their rank. Mine didn't and we ended up with exInfantry Cpls forgetting they weren't Sgts anymore bossing Sigs Sgts around (How hard can it be to put rifles into an armoury).
Was reinstated on the grounds the 'Blue book?' rules hadn't been applied incorrectly.
Depends on the unit strength, around my way you have no worries as long as you make the grade within two years. Face facts, every unit is short so pay and rank should not be a problem! If in doubt Vote with your feet!