There have been a number of studies on see and avoid. All have been very clear that it has big limitations. The UK AAIB have made the following statements following a fatal mid air in 07;
• ‘there are limitations in the human visual system that serve to make collision avoidance difficult by visual means alone.’
• ‘small targets may be hidden behind aircraft structure, such as the engine cowlings, canopy arches, wings, or struts, until very late.’
If you want to give yourself a better chance you might want to consider the PCAS systems. At £400 ish you get a lot of help for not much cash.
Rod1