Agreed -
Giving a global PvE incentive to the faction that currently controls an open-world PvP objective (or majority of smaller objectives) is a good way to get people out into the open.
The global buff is a good one. But need not be the only incentive. Personally, my favorite incentive was the ability to gain access to a special PvP-enabled PvE area with higher-than-average yields on resources from farming various monsters and NPCs and special boss-NPCs with end-game-level loot. DAOC called this area Darkness Falls.
One of the best things about Darkness Falls was that each faction always wanted to have access to it to PvE in. However, the PvPers also wanted to get DF back to their faction so that they could enter it themselves and clear out all the carebear PvE people who were just farming. Whenever the area changed hands, many people currently PvE'ing inside would quickly run back to their faction's entrance area, gathering to mount a defence against the first wave of opposing forces. At times, these "stair defence" battles would go on for hours. Many of my favorite memories of this game are of these moments.
But that's not all -
Logging out inside of Darkness Falls was always a gamble, because one would never know if their faction would still own it when they logged back in. For the solo-pvp'er, this presented a unique opportunity to engage in guerilla-style PvP against potentially unweary opponents. Typically, only one would only be able to gank one or two people before word got out that an opposing player was in the area and a posse formed to get them. But still, heck of a lot of fun.
