I think you can get just as good control with a split mainsheet setup as a traveler... but much less conveniently. It's usually easier to adjust a good traveler setup than to "tweak" the sheet, esp at the higher wind ranges, so having to adjust two mainsheets (often far apart) won't be as smooth or as accessible.
Also, more line on the cockpit floor..... On the plus side, less cost, the cockpit is clear of traveler obstruction and at anchor you can secure the boom very well with the two sheets pulling against the topping lift/halyard - much less tendency for the boom to swing in some waves and a more secure grab point too.
btw - re the Vang... a missing vang is not deal breaker, but should be way up on your list of things to do as soon as possible....
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"