I guess after lots of problems with expensive "high end" fancy stuff like HPE's and co I kind of felt resigned that all BMC/IPMI was kind of crap, and at least with SM's I felt less obviously squeezed. Like I said math will all be different for high end stuff and big herds. But neither Dell or HPE's struck me as "oh yeah that's worth an extra $300 on every single last server!"
Turns out, you can actually install X9 IPMI firmware on X8 boards as the platform files are still shipped. Might be worth checking out, if this improves things for you. It did for me.
Check out https://github.com/devicenull/ipmi_firmware_tools for unpacking (and repacking) the SuperMicro firmware. The developer just merged my patches making it work with some of the X8 boards. As long as your board is listed in /etc/defaults of the IPMI tree you should be good.
Kind of depends which generation of servers. I had worked with a lot of x9 and x10 (xeon e-2600v1-4) which was alright, as long as you don't mind outdated java (well the newest x10 bmcs do html5 consoles too, IIRC); but I recently started renting an x8 server personally, and it's worse... My favorite is when serial over lan just stops responding when you go from console redirection to os opened serial port (and back)... real helpful for inputting disk encryption passphrases. Oh well, I'm renting this server because it's cheap, it's also 10+ years old, and it works enough.