I'm pretty sure dcs doesn't accurately simulate the lift disadvantage of delta wings. For example the f 16 has a better climb rate and is respected by Rafael, gripen, etc pilots even if it's a worse turn rate on paper.
i think dcs like most flight sims would benefit from accurately simulating why straight wings were used in the first place- lift, the ability to turn and climb- because although delta wings win on the first turn they lose energy and can't vertical in real life.