Yea, go for more space. I have the 128GB 830 and because I rarely delete anything my SSD doesn't TRIM as much as it should. I read an article where they had a 512 GB SSD with half of it as overprovisioning in order to prevent this problem. What I mean is that it was an extreme example in a series of tests and benchmarks. Anyway, with a lot more space you will have better performance (no write amplification) and better wear leveling. And this would be in addition to (perhaps slightly) better performance (as per specs, e.g., 4k rand reads).
I wish I had bought a 256gb, of course. A lot of this is just price points, once you have settled on reliable SSDs.