Both the E3 and Z9 are big gambles.  There may not be enough time with either miner to even get the ROI.  Right now coins on equihash are talking fork.  So it makes the miner questionable at the moment.  If they don't fork GPU miners will start to leave in droves looking for a place to park their hash and the likely place is ethhash coins.  So up goes diff and down goes your chance of getting an ROI on the E3.

So I would only risk funds you are willing to write off at this point as a loss because the risk is pretty high.  Everything is in the air as the devs decide if they are going to fork or not.