Point 1) Miami is good enough for DHCP, in fact probably better than DX, which has very buggy DHCP handling.
Point 2) Hardware routers don't return a hostname anyway when you connect, so you were right to define your own.
Point 3) Miami/DX is quite dumb and needs hostname entries to be given a static IP address in its database. Yes, this sucks, and mean dynamic IPs on a LAN won't work if you use Samba.
However, there is a workaround. My router at least allows you to map LAN IPs to MAC addresses; so you can have your Amiga always use the same IP and yet still can use DHCP to connect. Its a common feature of routers so you probably have it too. You should try this. Then define hostnames in Miami's database for these IPs, and you should be rockin'.
