DustyStyx: Not particularly, but if you happen to have multiple bloodbaths going on the same network, or another IPX service running on the server, it would result in a communications error. Changing the socket number would be a way to fix the conflict.
For instance, if you had the occasion to try and run a Bloodbath between a Windows 2000 box and a Windows 9x box you had to change the socket number because windows 2000 had something running on the default socket Blood was configured for.
Deadzone: Ok. So my friend is able to connect (we're using hamachi). But it's lagging like hell, is there a less laggy method? Like can I port forward?
If you are on a LAN, you should only have to open up UDP port 213, in windows firewall for DOSBox to accept connections.
If you want establish a connection directly over the internet, you can set your router to forward UDP 213 to your computer.
portforward.com has a number of guides and probably has a guide for your router. It does try to sell you a utility that will do it for you, but you can skip the add using the link at the top right that says "Click here to skip this add..." to get to the guide.
As a note, you don't have to use port 213, you can use any available UDP port you might already have open if you just add the port number to the end of the IPXNET command: ie. IPXNET STARTSERVER 26000 for the server and IPXNET CONNECT #.#.#.# 26000 for the client.
Unless they are under a really bolted down network, the client shouldn't have to do anything on their end as far as opening ports for a connection. It's just needed for the server side.