Fullscreen VS Borderless
Most instructions result in borderless windowed (impersonating fullscreen). This is a common trick for manual PLP, with only one downside: no Crossfire or SLI support. Some game engines quite consistently allow fullscreen with SoftTH. The biggest of these is Unreal Engine 3. When SoftTH V3+ becomes available (shortly), more games will support fullscreen.
Monitor Setup
A good Manual PLP monitor combination is required, where pixels line up (& other more minor factors). Many different layouts that line up pixels well can be found here. Listed below are PLP setup sizes that are documented.
(Microsoft Flight Simulator X Steam Edition 2014, using layout 19-27-19 "Common Lightweight")