Bronze rated. Thumbs Down.
You don't have much of a load, but it will be on 24/7 for months or years. Gold rated minimum, platinum recommend.
Can you elaborate on why? States 5 year warranty?
It looks like you already received some good recommendations, but here are the specs on the PSU you are looking at.
https://plugloadsolutions.com/psu_reports/CORSAIR_RPS0063%20(CP-9020120)(CX450)_450W_ECOS%204818_Report.pdf A bronze rated psu is at the low end of the 80% efficiency certification. It would be fine for a home computer that runs 3 to 6 hours a day without much of a load.
We are running mining equipment at full throttle 24/7 for months or even years at a time. This would be considered enterprise duty.
The difference between you input wattage and output wattage goes to heat generation. SO the higher efficiency the smaller difference in input and output watts the smaller the heat generation from the PSU. We already have a ASIC or GPU that in the process is very efficient at converting the input watts to heat while hashing. Some people literally heat their house in the winter with their miners.
If the PSU is getting hot, then the connectors to the PSU are getting hot. Like I have seen the connectors go to 135, 145, 150+ degrees F, and start to smoke and then you have a burnt connector. The hotter a connector gets the higher its resistance to the flow of current, and it gets hotter and hotter, etc.
Most down time on miners is PSU related.
The ASIC is designed for 24/7 operation. The standard PSU is not.
The higher the efficiency and if you load is in the range of peak efficiency the less stress on your PSU even running it 24/7.
A server PSU is designed to run 24/7.
Obviously you load will be light with the 2 300 Mh/s Baikal cubes.
You did state in the OP "Best/Most efficient power supply"
Thank you for all of that input, based off everyones information provided I've decided to use this
https://www.amazon.com/gp/product/B009VV56U8/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 
