I may regret this having done this, but...
I have a 24V 200Ah battery coming from these folks (it's actually SpecializedPower.net who sells the batteries)
The reason for the "optional" is that they custom build the pack and you can specify the current that the BMS will handle. As far as I can tell, they'll put the battery in different cases, with either studs or Anderson connectors and each option is different size and weight. This *MAY* account for the spec sheet photoshop look, or maybe it is just shenanigans all around and I'll regret the purchase.
I have been waiting a long time, I didn't realize the battery was made to order, so it was a 4 week lead time. They've been responsive in the meantime and ask a lot of questions about the project and gave me (unsolicited) advice on the wiring to the inverter/charger (2/0 AWG) which makes me think at least someone is sort of serious about doing this right. I'm still cautious (like any Internet purchase from a new-to-me seller) I believe they will actually deliver me something. I planned to report back once I received it and could run my own tests.
I do have a FedEx tracking number, but the shipment hasn't made it to FedEx yet.