I bought several Sonoff mini4r to add some automation to my lights, and wanted to post a short review:

Pros:

• price is excellent. Got 5 for <$50 cad.
• Size is amazing, itsy Bitsy.
• Build quality feels good.
• Should be easy to flash, if my soldering skills were better, with exposed pads.
• Connected to my home wifi quick and easy.
• SonoffLAN easily picked them up, with full control.
• Detached relay mode works great, with switch fallback if wifi goes down.
• quick response time, under a second.

Cons:

• only rated for 10-12 amps, means I can't install this on switch controlled outlets.
• wish it had headers for flashing.
• wifi only, wish there was a ZigBee model.

In the end, I'm likely to buy more, and some Shelly units for where I need 16-20 amp relays.