On my truck braking feels generally the same, as does mileage. I'll be honest that mileage is hard to track with only 10K miles a year and I am always varying loads. I have seen some pretty low tanks while towing and some fairly high tanks while empty, which isn't a lot different than OEM wheels tires. I don't have much to back it up, other than observation and feeling, but highway mileage may be up a hair and city mileage may be down a hair.
Braking heavy when empty does make a lot more tire noise than my old tires thou.