Bitcoin is a fixed-gear track bike; ecash is a multi-gear road bike. Both translate my power to motion but are designed for very different conditions. I would never dream of taking my fixed-gear bike on a ride through the mountains; likewise, I would never take my road bike on to the track for a 200m sprint.

My point is this: both bitcoin and ecash work well together and separately in different circumstances. I would never bring my cold storage wallet shopping, nor would I store my life savings in an ecash wallet.