Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.
Yes I have a couple running ZFS systems now and have had zero issues. I'm not aware of any size limitations since the card in IT mode is basically a pass through. The only limitation is 4 physical drives per port. I have breakout cables available that will allow you to use 8 drives per card.