"Yes, but a word of caution. A 4 qt pot can be a safety hazard with a liquid fuel or canister stove, due to the amount of heat reflected back down onto the fuel."
A typical example of a liquid fuel stove is an MSR-XGK. With it, the liquid fuel bottle sits outside the windscreen, so it is completely immune from any heat around the burner. I've used 4-quart and 6-quart aluminum pots quite a bit with that kind of stove.
However, trying to boil 6 quarts of water in a big pot is not very efficient. The 2-quart and 4-quart pots work a lot better. About the only thing I would use the 6-quart pot for anymore is for snow melting.