You asked-- "So, you're suggesting that USB 3 would be better for connecting to the external"
I didnt so much suggest it as imply thunderbolt with conventional HD is no faster, and a hair slower than USB3.
Its "better" only in the sense that Thunderbolt drives are much more expensive.
you didnt mention which device/computer, your old one or the new one you implied on getting, i.e. the new Air.
USB3 external HD are as common as water, theres no worries of cables at all, they all come with same.
LaCie is just a Seagate drive (if a conventional LaCie), ..... there is no such entity as a "rugged hard drive" as meant a conventional HD, they all have armature bars, heads, platter, spindles and heads that hover Nm above the platters.
Theyre tougher than they used to be, but still fragile, and ANYONE that has put their faith of data in ANY single HD has always lived to regret it.
"Seems whenever I look up USB 3-anything, the search engine produces USB 2"
Thats because all the new USB3 drives are backwards capable with USB2 ports on older machines.
âž•Given the second law of thermodynamics, any and all current mfg. HD will, under perfect storage conditions tend themselves to ferromagnetic layer depolarization and a point will be reached, even if the HD mechanism is perfect, that the ferromagnetic read/write surface of the platter inside the HD will entropy to the point of no return for data extraction.
HD life varies, but barring mechanical failure, 3-8 years typically.
best options for the price, and high quality HD:
Quality 1TB drives are $50 per TB on 3.5" or $65 per TB on 2.5"
Perfect 1TB for $68
http://www.amazon.com/Toshiba-Canvio-Portable-Hard-Drive/dp/B005J7YA3W/ref=sr_1_ 1?ie=UTF8&qid=1379452568&sr=8-1&keywords=1tb+toshiba
Nice 500gig for $50. ultraslim and perfect
http://www.amazon.com/Toshiba-Canvio-Portable-External-Drive/dp/B009F1CXI2/ref=s r_1_1?s=electronics&ie=UTF8&qid=1377642728&sr=1-1&keywords=toshiba+slim+500gb
2TB compact Toshiba 4-platter drive, very small, high quality and very cheap (have several of them) $119
http://www.amazon.com/Toshiba-Canvio-Connect-Portable-HDTC720XK3C1/dp/B00CGUMS48 /ref=sr_1_4?s=electronics&ie=UTF8&qid=1379182740&sr=1-4&keywords=2tb+toshiba
*This one is the BEST external HD available that money can buy:
$75
HGST Touro Mobile 1TB USB 3.0 External Hard Drive
http://www.amazon.com/HGST-Touro-Mobile-External-HTOLMX3NA10001ABB/dp/B0062FZ2WS /ref=sr_1_1?s=electronics&ie=UTF8&qid=1379185002&sr=1-1&keywords=hitachi+extern a l+hard+drive
Most storage experts agree on the Hitachi 2.5" as "best quality that money can buy in conventional HD"