well your getting NSW for a water source...so its better then mine...I have also started to top my tanks up with tap water every 2nd week (previously in my old tank I topped up with tap water every week after the cycle was done). So I am not thinking it has anything to do with water parameters (I do not even have heaters on my tanks...they have never been phased (none of my species)) to go with the fact that your using NSW well the species alone is very tough...its often marketed as a spearer that is a smasher at heart...they aren't "typical" spearers...they are abnormally interactive (spearers normally do NOT interact) and there relatively aggressive (all stomatopods are aggressive but its the spearers that retreat first, less keen to fight)...this species is not among them and acts more like a smasher, another reason which makes it attractive for the aquarium, due to that nature alone makes it a species often seen out of its cavity searching the tank (rather then other spearers that will sit in there cavity 24/7 waiting for things to come to THEM, like all mine). Finally one of the best things about this species (to go with the above) is as I have stated previously...the coloration is simply amazing, it can vary rapidly and extremely (as to how no one has any real evidence to support anything just claims).
Lets not forget the ever unique eye pattern, (mark it in your brain) since Spike is the only species known to posses the unique pattern (all of mine are a single pattern Bronze or Silver except for The Leviathan whom has a dark based with light gold dots covering it).
so the fact that Spike :D......
Is a spearer (I just love spearers even though I only have 2 :()
Is a tough species (survive bright lighting, fluctuating parameters, etc.)
Is a interactive species (Going to be seen often, not hiding like the rest etc.)
Is a extremely colorful (species prone to changing color rapidly & vividly etc.)
Is a moderate sized species (not so small it cannot be seen, not so big that it would need special requirements (DSB) etc).
Makes that whole package (Spike :D) one hell of a good marketing animal for a stomatopod display tank and another reason to why there often acquired and asked for.