I have a bunch of LSI controllers, including the 9211-8i. It used to be a popular controller a decade or so ago, but it's downside is the high power consumption in conjunction with a tiny heatsink that will fail to dissipate the heat properly unless you have a 2u enclosure (or a 1u with a riser) with air pressure optimized system fans. In fact, even with a 2u enclosure, the 9211 will get quite hot (80C-ish over here in my Supermicro CSE825), and if that heat is registered by any temperature sensor, your cold zone fan(s) are going to turn crazy... and fail to heatsink the 9211 nevertheless, because it's tiny heatsink is insufficient. With supermicro rack chassis of any flavor there's a trick though: you can widen the air shourd at the fan wall side, while keeping the exhaust side condensed, which will result in the shourd bleeding air onto the topmost PCI slot (might not work for CSE743 / 745 enclosures because those have exhaust fans that pull air which reduces the bleed effect). If you install the 9211 into the top pci slot and can have bleed air there, the bleed air from the shourd will push the 9211 below 50C.
My recommendation would be to use a 9300 or 9400 even if you can bleed air on the 9211. The 9300 uses 10W less power then the 9211, the 9400 uses even less power then the 9300 and overthe lifetime of the controller these power savings will accumulate into power bill savings larger then the price difference of the 9300 to the 9211. The 9300 has a larger heatsink, probably twice as large as the 9211 on top of using only a third of the power, which makes it more heat manageable. The 9400 has a _huge_ heatsink covering the whole card (easily 10 times larger then the 9211) while again using less power then the 9300, the supersized heatsink handles dissipation so well the 9400 probably can be operated just fine inside a desktop chassis w/o front-to-back airflow optimizations.
FreeBSD-15 can use the 9211/9300/9400 series controllers out of the box.