Had 10speed ultegra groupset on my old bike but it started having issues with the shifting - I eventually traced it to the front shifter but you can't get new replacements anymore. So bit the bullet and went with whole new 11 speed Ultegra groupset which has given the old bike a new lease on life. Ultra smooth trouble free shifting once again! Just as good as the Dura-Ace shifting on my top end bike.
All the mechanicals on this derailleur are just that much easier to set up and adjust compared with the old Ultegra.
Moving from 11:28T to 11:34T this shifter does the job. It’s has made the setup noticeably heavier but that is to be expect when increasing the cassette as well.