I have only one Tretakt and it's working good in my small-ish Zigbee network. From the Zigbee Map, I can see that it holds fairly strong connections with most other repeaters (no red lines) and it is acting as parent for 4 battery-powered devices (they work fine, no miss-fires).
But yeah, this is just one datapoint, from one user, with only one device; and I'm also an IKEA fan 
Make sure you use the latest firmware and update if necessary; you can do that directly from Hubitat, without going through IKEA hub/app.