Nick,
I don’t have Arlo but I can give some perspective on Blink/IFTTT/ST interface.
Since Blink is owned by Amazon, all official integration with ST was cutoff some time ago. IFTTT works for arm/disarming and motion detection. Looks like Arlo has similar options.
IFTTT is my opinion has always had latency issues. The response rate with Blink/IFTTT is somewhat lacking, sometimes up to a few minutes to register motion detection. Arm/disarming is usually faster but still in the 10-20 seconds range. It is an IFTTT issue, Blink issue, or combo ¯_(°_°)_/¯.
A big downside to the IFTTT integration is that it is one way communication ST to Blink so if you manually arm/disarm Blink in their standalone app, ST is unaware. Not sure if that applies to Arlo as well.
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