Due to the ongoing development (cost per gig) and unproven long-term reliability of SSD. I would recommend SSD only for your PCs (laptop or desktop) on-board storage.
On-board SSD can really, really boost performance of your operating system and other software as 'reading' commands and data from it is extremely fast compared to reading from an on-board HD disk; however ... SSD is quite expensive per gig of storage currently and there are questions regarding 'life expectancy'. On-board storage speed is also a factor in memory paging activities. External drives (of any type) should never be used for operating system files or the paging file, thus external drive speed does not effect overall system performance really.
Additionally, external data storage will always be impacted by the I/O port data transfer rates (ie: USB 1.1, 2 or 3, FireWire, etc) and by what else is running that is also competing for external resources (ie: how busy is the I/O buss with CD/DVD/MP3, internet, etc), where most motherboards are set-up to provide as fast as possible access to the on-board storage.
Both SSD and HDs must be backed-up as failure can and will happen. Counting on a 'disk recovery' service is not really practical or cost effective (unless you have a significant "business" investment in the data in which case you should have a full fledge disaster recovery plan/service in place). Disk recovery attempts are largely successful; however obviously they cannot guarantee success. Additionally, often you have to send off the bad drive, provide a new drive for the salvaged data, and wait 1-4 weeks for the recovery firm to get back to you ... that is a long time nowadays.
By the way: Buying and connecting a 1T second external hard drive and getting a solid backup software package can be done for $100-$150. That is probably much less than the cost of paying to 'hopefully recover' your data (and you don't have to wait a month).
The only argument for getting SSD currently is the trememdous increase in I/O speed from that of HD. That speed advantage is readily apparent for overall system performance only if SSD is configured internally.
To me, to get decent 'bang for your buck' don't use SSD externally (until price drops very considerably).
Happy shopping.