To further emphasize the "need for speed", I recently purchased 2 Samsung 850 Pro 512 gig SSD drives (got them for a super price!). One of my external drives (with a Seagate mechanism) was "going bad", as TechTool Pro kept telling me, and thus it needed to be replaced. I enclosed one of SSDs inside a nice, slim Orico external enclosure (easy installation), connected it to one of my Macs, erased, formatted, and partitioned it into 3 partitions. Two of the partitions I use for backups for each of my Macs.
Well, yesterday, I went through my normal disk cleanup/maintenance/repair, and backup processing. I still have a 1 TB Seagate External drive with 3 partitions (again, 2 of them for backups for each of my Macs), and it spins at 7200 rpm. I connect that drive via Firewire 800, and the Orico enclosure via USB 3.0. Well, I was blown away by the backups I did yesterday. My Mac MIni has a Samsung 840 Pro 256 gig SSD drive, and my MacBook Air has a Samsung 840 EVO 252 gig SSD drive (I believe that is the model). Both of them have the same amount of "stuff" on each, less than 85 gig worth (I like to keep my Macs "lean and clean"). When I ran SuperDuper! to do the backups, it took ONLY 10 minutes to backup to the new SSD, but over 30 minutes to backup to the Seagate drive. And that happened for each of the two backups I do for each machine.
Also, given that SuperDuper! makes a bootable backup, booting up from such a backup definitely satisfies my "need for speed". I am seeing similar differences in booting up either of my Macs from each of the backups.
I am going to give the other Samsung drive to one of my sons for a Christmas gift, but I am definitely going to replace the external Seagate drive with an SSD (even though the drive is fine. I'll try and sell it). As it is, the 3 partitions I have on the new SSD are 100 gig, 100 gig, and 312 gig. For the two smaller partitions, given that I use each of them for backups, I need to keep the stuff on each of my Macs as lean as possible. While I might need to download an occasional large file (typically a movie or a TV series), I would need to "move" it to that larger partition on the external SSD drive. So to possibly alleviate all this, I might purchase a Samsung 850 Pro 1 Gig SSD drive. We'll see.