icr and imr are different battery chemistries.
icr = not as safe (hence the protection circuit some add), higher capacity, lower drain rates
imr = safer chemistry, higher drain rates, lower overall capacity.
my IMRs are genuine AWs or EFESTs ... all of my ICRs are non-protected sanyos or LGs that i got out of laptop batteries with failed protection circuits.
and before anyone lectures me, i trickle and discharge tested them before using them in mods.
the SID has protection built into the circuit, so using "protected" icr batteries is redundant, and i would not worry about it unless you are using a genny with a super low Ω coil ... anything above 1.4Ω should be OK, unless you are trying to pump more than 15w through it.
high drain IMRs (not the hybrid ones with added protection) are my choice for mods that boost ... they can handle the discharge rate without danger of heating up. but, i tend to vape my rebuildables between 10w and 13w ... my carto tanks tend to be comfortable at 8-9w.
a 2000mah EFEST imr lasts as long in my VAMO as a 2600mah Sanyo unprotected icr. i am always boosting in the vamo, except for that small window when the battery is fresh off the charger, and i have a 2.2Ω carto in my tank, and it is set at 8w. after the first few tokes, i'm boosting.
i have noticed that anything below 2Ω on the vamo with a single 18350 will heat the whole thing up if i go over 9w. battery gets warm, control head gets warm ... but the 18350 drain rate is much lower than the 18650 drain rate.
if you are really worried about protection, make sure you have a real hotspring in your mod, and shell out the $10 for a holocron labs ShortStop or a resettable 2c fuse.