Another limitation to be aware of as an audiophile are the supported codecs. Shure dropped support for aptX HD compared to the BT2. The TW1 support SBC, aptX and AAC.
My Android phone connects to my car using AAC, but for some reason it refuses to do so with the TW1 and uses aptX instead.
My BT2 connected using aptX HD.
The Shure app allows you to select what earphones are connected to the TW1. It then drives them accordingly. The BT2 had no such setting. The setting definitely does something, the sound signature changes when you change the setting.
My initial impressions on sound might be wrong due to different fit and seal, but compared to the BT2, the TW1 appear to drive my 846 more flat when I set them to 846. When I change the setting to a 535 or 435, the sound becomes more boomier and reminds me of the BT2. But take this with a grain of salt until more people report it. Placebo and different fit can play a role here.
Lastly, the fit. I only used them at home so far but I intend to take then on a hour-long walk later today. First impression is amazing. Cable and BT2 never stayed so securely in place.