IMHO, a good idea to replace the Corsair if its >4-5yrs old.
You'll have some capacitor degradation over time, so need to consider that.
With the config posted, you'll probably be running at ~400-450W, or about ~70-80% of your Corsair PSU capacity when at peak load (eg gaming). If this usage is rare, then you could get away with the older PSU, but if you see heavy loads on the machine for most of its usage period, probably better to upgrade the PSU.
Regarding the Antec itself - I have no experience with the brand, just ordered an Antec HCG Extreme myself, so will know in a few days i guess. Hopefully somebody else can give feedback on the specific model.