what climate do you live in? if your average annual climate is dry and warm, go to 465. If you grow with lower temperatures and a humid climate, go to 600.
so you should be able to optimize the electricity consumed for extractors, heaters and dehumidifiers.
use cal / mag .... enjoy your led
(I would go with the 600 in all my life in 4x4 I have a test here somewhere on the forum with cuttings under a cob cxb .... 500watt / 600/800 the 600 is the right compromise and as they have already said you can always mitigate it but if the situation requires it go
go to lumatek 600 pro 2.9 i am going to buy the 1000 for a 5x5 you will not regret it i used their ballasts for years once one broke i went to the store changed in 5 minutes and came home without worries