Coming from an actual RCF owner, it is not a compromise at all. End result is a brilliant chassis that handles extreme loads with high torsional rigidity. The entire chassis is constructed as a unibody just like any other chassis. Just the initial design was using existing three chassis to make one out of it since a brand new platform would have costed more. The extra weight is due to extra chassis rigidity over and above what a normal performance based chassis would be. The reason for that is, the original plan was to make a convertible without the need for added reinforcements (since the chassis/B-pillar are not there on the Convertible). Still, that extra chassis rigidity makes the car far more confidence inspiring at the limit. The added weight is not because of the Frankenstein chassis, but because a convertible was planned as well.