Is the Etek going to need HP or LP tanks? Or won't it really matter as long as the tank reg has good flow and recharge?
If you will buy a new airsystem anyway then get a HP and be on the safe side.
If you allready have a LP try it out.
It might work or also might cause some problems due of some bad rechargerate of some LP's.
Just the same game as on the EGO.
Don't forget, the internals in the inlinereg of the ETEk are the same as on any ego.