Yea, after I made this post, I was actually able to contact someone directly at Buffalo. They explained to me that the firmware for these multi-drive units is on the drives themselves. Therefore, upgrading ANY of the hard drives would require restripping across EVERYTHING. And data would then also be lost if you did this.
Due to this, these might actually not fit my needs. I was looking for something that would allow me to easily upgrade one of the drives if needed. I am new to RAID configurations, but I understand that depending on which RAID mode I am using, removing one drive could affect others. I guess if I have it in RAID 0 (I think), that would mean all drives store data independantly from each other and upgrading would be the easiest (and storage would be maximized). This is probably what I was looking for.
I have an older Buffalo Drive station (500GB) and it has been working great compared to some other brands I have purchased. Therefore, I was hoping to maybe get another. Is there a Buffalo NAS product (not USB only) that can allow for easier swapping of internal drives? Or do most of Buffalo's products store the firmware on the actual drive itself and you have to be careful?