I read some old discussion about Serie 5 fighters and have different opinion on the conclusion.
First,I don't believe Re.2005 can fly out the same top speed at three different altitudes,even P-51 can't make it.In Italian Wiki,it seems to say Re.2005 can reach to 678km/hr at 2,000m but only 628km/hr at 7,000m. Although some articles say Re.2005 has the fastest speed at high altitude,but German test report mention about only the G55 was competitive with its German opponents also in term of speed and climb rate at high altitudes still maintaining superior handling characteristics.
Other resources report after Re.2005 could dive to 988km/hr in test flight,structure problems still remain in later air combat.These caused some pilots need to abandon plane in combat flight.When designer got idea,Armistice day was coming.Reggiane industry had no chance to fix whole bugs on Re.2005.
MC.205's top speed appeared at 7,500m but the plane almost lost control and easy to stall.Its performance dropped considerably over 8000 meters.
Maybe Fw190A can beat all Italian fighters at low altitude,but German needs to against Alliance bombers over 30,000feets,Fw190A also dropped performance considerably at high altitude.
Only G.55 got excellent performance at every altitude and heavy fire power.So,I think German choice is right and reasonable. G.55 is the best Axis fighter in 1943 and good enough to replace both Bf109G Fw190A.