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.
There's not going to be any forks. All you folks spreading that need to read this article;
https://blog.sia.tech/the-state-of-cryptocurrency-mining-538004a37f9bIf you don't read this in it's entirety, you'll never understand the ineffectiveness of forking Coins, to combat ASIC. It DOESN'T WORK. I'm sorry to break it to you, but GPU mining is dying and will be dead. I'm not happy about that, but it is the reality.
Not saying anything about the E3 or Z9, but it worked pretty well for Monero.