I will not use a spacer. This has come up in other threads, and so far what's missing here is that it's not just that the atty will keep firing, but what could happen if the batt detonates (or some such). I'm certain Vapage will never endorse using a spacer on the batt.
Better safe than sorry.
As in other threads, i take the side of, if it's a matter of a few dollars more for the right batt, why risk it?
I find the AW IMR fires pretty easily.
I have some flat top 2600 Tenergy's that work too, they are longer so the firing pin does touch; they do compress the spring more and last a good long time, but the IMR's from AW give a better performance for the LR's i use, and they last longer than i expected; like at least all day.
BUT, I am using the batts from Vapage!!, the button does not always make contact without pushing HARD, so enter the spacer!