There’s been some buzz over on other forums that Aerocoach measured Corsa G+ 2.0 TLR’s to be not as fast as bicyclerollingresistance’s website claims (link at bottom).
Secondly, even if Aerocoach’s data were wrong and Vittoria’s were indeed faster or equal to equivalent TLR race tires, another very common topic of concern around the Corsa G+'s is its tread patterns are prone to retaining glass shards and debris as have been observed on the clincher version. Granted, it’s tubeless so the idea is to let the sealant deal with it. And if you’re doing a TT on a good course this becomes even less of a risk. That said, I like mitigating equipment-related risk when it’s time to execute…
So to answer your question, if it were me I’d use the not-as-light but maybe actually faster and more puncture-proof GP5kTL’s. Because Crr & reliability matter far more than weight in a (flat) TT. 