I've got the DBrand Killswitch case on my Steam Deck, and I bought this dock knowing that it might not be compatible with the case (I mostly wanted the dock for peripheral connections), but it fits in the dock stand relatively well.
The stand attachment on the back of the Killswitch case butts up against the dock at the back and allows it to sit in the groove where you get a decent playing angle. You can angle it forward a bit further and the rubber on the bottom of the dock and the case do a decent job at making it stay upright if you're playing with a controller and not moving it around. It's not at risk of falling because of the stand on the back of the Killswitch, but if you've taken this off for another attachment your mileage may vary.
The Steam Deck won't stand up in the dock if you have the Killswitch travel cover attached – but the cable can still be connected for charging if you need that.
I haven't tried the HDMI connection, but power passthrough, the 3× USB connections, and ethernet port are all great for what I need, and the SD card slot is perfect for further expansion beyond the SSD + internal SD card on the Steam Deck.
At about a third of the price of the official Valve dock, I'd say that this Nyko Dock is a great alternative to consider – the only thing you give up is the displayport connection, but you also gain the SD card slot.