Your post seemed more like a passing comment than an official "don't use it". Guess I'll re flash back to P16 and roll back FreeNAS until SM comes out with the newer firmware unless you think flashing the on board controller on X10SL7-F with the 20.00.04.00 from Avago is safe to do.
iXsystems doesn't make public statements about things like this. I said it only because I have inside info. iXsystems, by the virtue of not having total control of all of the hardware that FreeNAS runs on, prefers to be silent and let things go "as they may".
So take it like this. Internally, at iXsystems, we don't use anything except 20.00.04.00 because of the known problems. TrueNAS systems have their own auto-updater for the LSI firmware, and it updates to 20.00.04.
So you have the potential to use 20.00.02, but *I* personally wouldn't recommend you use it because of my information on the topic.
Likewise, you can choose to update LSI controllers that are on Supermicro motherboards with LSI firmware equivalents, or you can simply wait for Supermicro firmware to be released. The downside to using LSI firmware is that you'll lose the ability to identify the Supermicro brand cards forever (well, without some real work to bring it back).
LSI controllers get their identity from the firmware. So if you flash generic LSI firmware, you'll have a card that thinks (and behaves) like generic LSI firmware for the specific card firmware you flashed.
Here at iXsystems, the TrueNAS systems are updated with LSI firmware for the onboard systems. Here's the conversion we use:
LSI 2308 controllers on Supermicro boards are reflashed with 9207-8i
LSI 2008 controllers on Supermicro boards are reflashed with 9211-8i
Note that this is proven to work on TrueNAS hardware. Your hardware may or may not work properly with this firmware change. Frankly, it may even break the LSI controller in some permanent, unrecoverable fashion.
The conservative answer is that if you are using a Supermicro brand motherboard with on-board LSI and you don't want to take a little risk with using LSI firmware, then you should contact Supermicro and let them know you want 20.00.04.00 firmware and for them to make it publicly available. I have talked to AsRock Rack on behalf of FreeNAS users and they are working on a P20.00.04 that is compatible with FreeNAS 9.3.1. I can expect that if customers contact Supermicro that Supermicro would make it available also.
I'm still on 9.3.0 just because I've been too busy to care about upgrading my primary server. My Mini is on 9.3.1 though. I don't feel like 9.3.1 is so critical that you should spend too much time worrying about being on a previous release unless you have some bugs that are fixed in 9.3.1.
HTH.