Sorry I don't understand your throughput statement. The T3 is a JBOD enclosure since all RAID functionality come from OS software. So what is the difference? My understanding is that each drive has a separate dedicated SATA III controller for the fastest throughput.
Single Drive Mode
It's an educated guess, but TB externals with Platter drives are either no faster or in some cases slower than a USB3 external with the same HD installed. Keep in mind I'm assuming Late 2012 and newer Macs with UAS support and USB3 cases with the same UAS chip support when I talk about transfer speed. Again, a SINGLE drive - no RAID.
It is known that a 4tb 5 platter HD in some external USB3 cases (CalDigit AV Pro is one of a few) with reach 190-200 up and down. Smaller drives with less platters will be a little slower. Since you have a T3 at hand, you could take a single drive out of the RAID config and run Blackmagic on it to find out how it does.
An SSD in the T3 will be very fast. You can't make any HD go faster in single mode. If you get something higher, I'd love to hear about it. So would Caldig. The box is designed to task in RAID.
These are the numbers from Mac Performance Guide (so far the only review)
MB/sec:
Single drive: 184 write / 181 read
2-drive mirror: 184 write / 198 read
3-drive mirror: 184 write / 271 read
Note the write speed is constant - interesting is the fact that I have the exact same drive in one of my AV Pros (USB3) and get a slightly higher number.
This test is with 2TB Toshiba/HGST (Really Hitachi) drives, so larger than the 1TB and likely a little faster. The 4TB drives I tested over USB3 were HGST 5 Platter and my results were much like what Mike at BareFeats published. Very close to 200.
Real world performance will be up and down from the top numbers.
Obviously, the RAID speeds and versatility are where the action is on the T3.
Once you determine it's a quality device, the numbers fade and you work...Happy
