Security wise Nano is DOA. Currently any attacker can effectively DDOS the network with trivial resources. I’ve personally proposed a complete solution to this problem over a year ago but it’s implementation is complex and would require a network split and my proposal has effectively been ignored in favor of other mitigation’s that fall far short of protecting the network. I’m not a security researcher and hell I’m not even in the CS field anymore so if I could figure out and implement an network wide attack on my own the barrier to entry is low (to be clear I have not executed any such attack). If you want to read further, the issue is a precomputed PoW attack. Nano’s very benefit - speed - is it’s biggest pitfall.