If you're putting together a workhorse group, going sub-primo on the cassette makes a lot of sense. It's the first part that'll wear out if you're logging serious miles, and since it sits at the center of the wheel, its effect on rotational weight is quite low. Shimano's Ultegra 6800 Cassette consists of 11 steel cogs riveted onto an aluminum carrier that'll help reduce wear on your freehub body, and comes in a wide variety of gear options, from a corncob-like 11-23 to a spin-to-win 11-32.