actually, it is just as simple as changing the brake and lever. it will shift 9070, 6770, and 6870. the levers are dumb, all indexing is done from the rear derailleur.
@stan kerplinski true, good point, if you have di2 (ultegra), you could upgrade to these, but people wanting them but don't have di2 already have to buy more than levers, calipers to get a working system unless riding singlespeed. thanks for pointing that out, i guess we were unclear. we'll update accordingly.