I have a similar setup. Even for hard drives and slower SSDs on a NAS, 10g has been beneficial. 2.5 gig would probably be sufficient for most of what I do, but even a few years ago when I bought my used mellanox sfp+ cards on eBay it was basically just as cheap to go full 10g (although 2.5 gig Ethernet ports are a bit more common to find built-in these days, so depending on your hardware, that might be a cheaper place to start). But even from a network congestion standpoint, having my own private link to my NAS is really nice.