Mmmmm...i smell the blood of math fails.
1 gbit = about 100MBytes
10 gbit = about 1GByte/second
1 SATA 6Gbit can* copy at 5.6gbits or 560MB/s
1 PCIE SSDs can* copy at 3.5GB/s or 35gbits.
A regular 5.4k 500GB hard drive can push 100MB/s
A regular 7.2k 500GB hard drive can push 150MB/s.
Newer regular 7.2k 2TB+ drives can* push closer to 200-220MB/s ea.
Hardware raid with large onboard RAM cache's coupled with SSD caches can sustain at whatever level it can be fed just about (not really, but kind of since we're talking about peak total bw rather then IOs)...
Software raids typically peg out at the peak of the total bw of the SATA ports it applies to (and most little intel setups with regular hd's you are going to see max 150MB/s, might see a little higher...but longer term sustained will be closer to 150 [you could see 1GB/s with the right/wrong unraid 0 setup...but who wants to fail at raid]).
So a 1gbit connection = fail for ssd's, or even regular hard drives if you want to be able to transfer at peak speeds. When i moved 10GB of data from my 250GB samsung pcie ssd to my 500GB samsung non-pcie ssd (with samsung RAM caching on...[typical max on it is 550MB/s]) i hit as high as 1GB/s during that transfer (again only because of the ram caching...normal high is 550MB/s). Again, 1GB/s = 10Gbit, so if you want to backup your pcie ssd to another backup device hourly (and thats full backups) which has caching to allow for faster transfers (as in high end backup server with raid and onboard caching, or ssd caching...), then yea you'd totally need it.
If you are running an Exchange email server with 250 people whom get 150 emails a day, mostly text based, and a half filled 1 TB of space on SSDs for your exchange db(s)...most organizations will not need 10gb. You will barely need 100mb internally and only 10mb externally (actual internet). Only for backups would you ever need more then 100mb, and thats assuming you needed to do a full backup or restore over a very short period. 10gb is nice, but not worth the cost until you get in to more Enterprise worthy setups most of the time. As a fellow nerd, is 10gb better? Yes always. Is it worth it? even in Enterprise org's, not usually. But its not the usual times that you buy it for, its for the emergencies when you need to restore data. (or if you are a highly specialized org that works on video's over a network connection, or something like FEA over networked servers, trying to pull back the completed data to individual workstations on a fairly regular basis...or running 10gb+ between core switches makes sense...etc).
ps - if you like that i replied to this year old thread, so i could soapbox this bitch in to shape, feel free to upvote. =P