Aspiring techie :
but having a bigger SSD will improve reliability
How so? yes you'll have a bit more spare capacity, but you'll just fill it, that's kind of the point of a drive. In terms of endurance, it'll be the difference between 5 years and 6 years, I'd say not important. By far the bigger issue when it comes to reliability is the specific choice of drive.
I'm not convinced that the V300 is great, and it seems to be a weakness in a $2.2K system to have that level of storage. Get an M2 drive? if you have an M2 port on the mobo.
OP, might be an idea to wait for the next intel launch, after all it's meant to be in three weeks?