No one has replied to this so with my limited knowledge and zero experience with SSD's ;) I will chime in here... I think the idea, or one idea, is to use the SSD to be able to reduce the amount of RAM you have to buy, or use, in your system. I don't think you can entirely substitute one for the other. SSD is not as fast as RAM, RAM is not as cheap as SSD somewhere in the middle find a workable solution. As far as I know VSL software does already stream from the drive - and uses both RAM and the drive to find a balance for performance and efficiency depending on your system. Having an SSD just means that the seek times and read times are much faster than a hard drive, so the software can budget keeping less of the sample in RAM and more on the drive, knowing that it can find it and get it when it needs to. So, for example, if you were going to buy a machine with 16Gb ram and use normal hard drives, with an SSD configuration for your samples you might get away with 12 or 8Gb or RAM, save the money on ram and put it into SSD drives instead. The net benefit is that SSD drives last longer, are less likely to fail than a hard drive and your projects and new articulations will load much faster.
If I got any of that wrong somebody please say so, but that's my understanding of it anyway.