Will this work for a group of 5-6 or should...
Will this work for a group of 5-6 or should I get another pot?
It really depends on what you're cooking. If you're only boiling water, you should be fine. If you'll be cooking meals in them, I find these two to be a little small. They're just about right for 4 people, but with 6, you'd want something else to supplement it; maybe another 1.5 or 2 liter pot. Going with MSR would allow you to use the same lid/heat radiator/ and any other size specific accessories - but this is of course not necessary.
Unless you're committed to stainless steel, another thought would be something like the hard anodized aluminum MSR Flex 4 set (item# CAS0545) with a 3.2L and 5.3L pots. You get a good usable volume and versatility, whether you want to just boil water or cook a meal for that many people at once. As Knanier says, the difference in what you have planned makes a huge difference.