Hey smoke,
Be careful when chosing a wetting agent, some contain anti fungicides and anti bacterial substances, not what you want when applying the Essence.
If the shop you are purchasing from doesn't have the bio-wetter then it is fine to apply the essence without the wetting agent. Yes the wetting agent adds many upon many benefits, but if you're unsure what others have in them then it is better, imo, to not use anything at all.
Just so you are aware, the "wet Betty" you're refering to is not 100% concentrate. Yes it contains a Yukka extract, but it does not say in what form / dilution. I was with the Advanced distributor a few months back now, we poured them out side by side and you could tell the "Wet Betty" had been dilluted down quite considerably (who knows with what). My ethics is, if you're buying a yukka extract then that is what you get with the bio-wetter.....100% concentrate, this is why it is a tad on the expensive side.
Hope this has been of some use.