[erincandescent]

I've seen lots of pretty terrible experiences with the i40e and newer Intel drivers.

For newer NICs than the X520s I'd probably grab a Connect-X card.

[mwpmaybe]

They've been stable for me but I'd be lying if I said I'd only heard good things.

Looks like prices on the E810-XXVDA2 have come up since the last time I looked while prices on the ConnectX-6 Lx have come down, so that'd be a good option!