Do you absolutely need wire,no. Before switching to wire i caught ton of salmon off mono on the dipsys. The wire makes a big difference though. Get much deeper and faster with wire. The strikes from salmon on a wire rod is unbelievable and the feel of a salmon on wire is a whole different animal. You feel everything, every little headshake.
If i were you just get one spooled up with wire. Once you get the first one on wire i am pretty sure you wont mind spending the extra cash on it.
No more setting the hook 15 times then reeling in 100 feet just to keep setting the hook trying to pop that dipsy with 300 feet of mono out there. I so dont miss that. One gentle pull and the dipsy pops with wire. So many advantages to wire, i am sure if you run one this year with wire and get a few on it you will be switching to wire on all your dipsys