Trim really is only a helpful message when the drive is near full so the GC can preemptively zero blocks and retain good write speed. Without trim, the firmware must wait until it gets a write for a particular block before it know it can be erased.
If your drive has reasonably with unprovisioned space, it can simply work around the missing trim commands - this however, is theory, I do not know if the firmware actually does this. This is the exact thing that makes some drives better than others when working without trim.
Thanks. I'll probably end up creating an unprovisioned partition. It's frustrating, exactly because of the uncertainty re future performance. Especially given the price premium for pro/enterprise level hardware.
You can research if the firmware understands MBR and GPT - if it only understands one, then you have to use that. Alternatively use Samsungs own software (I think it's called Magician, can't remember exactly), it will make sure you have the unprovisioned space setup correctly.
If your drive has reasonably with unprovisioned space, it can simply work around the missing trim commands - this however, is theory, I do not know if the firmware actually does this. This is the exact thing that makes some drives better than others when working without trim.