VirtualBox: better NAT port forwarding, or classica Bridge ?

[Christopher Bianchi]

Hello !
i'm setting up a ubuntu server as guest in virtualbox. My question is
this:

for the point of view of security and performance is better to configure
the guest OS in virtualbox with:

1) NAT portforwarding as explained in the virtualbox tutorial (with
VBoxManage)

2) or the classic Bridge ?

another question: if i choose the second choice, is it possible to put
the guest os in DMZ by my router ? so, is it possible for a guest OS be
in a DMZ ?

thanks!!