I don’t know about iDRAC but I used raritan a bit for some home projects and it’s not super fun. I couldn’t connect it on HDMI when the server was already running, it had to be connected before the boot. For both VGA and HDMI, it sort of works, there is a clunky but functional java desktop application, the screen is often off by a dozen pixels (part of the screen hidden) and the pointer too.
For new servers, I just buy a supermicro motherboard with IPMI and stop worrying. You can set up an IP based firewall within IPMI, so that only a handful of IPs can even connect, plus a very strong password, and I am not too worried about exposing it to the WAN (I know it’s not a great idea but I don’t know any alternative that doesn’t require another U in a datacentre)..