The v-led 8w 921 LED replacement are just as bright as the Nitehawk or Silverstar replacements, which are both lame and available usually at your local autopart or dept store. The only reason to use an LED 921 is to use the power saved for other reverse bulbs like the vled license plate frame:
http://www.v-leds.com/Exterior-LED/...e-LED/V-LEDS-HIGH-POWER-18W-p7516915-1-2.html
921 LED upgrades are not worth it unless you make your own. The 5w and 8w 921's are NOT made for non-stop usage. After a minute, they'll overheat. So, only use them to back-up and don't leave vehicle in reverse while doing whatever.
Upgraded 1156's for reverse lighting are plentiful in most autopart stores, and are usually 35-50w. Check your reverse light fuse, usually 10amp which will tolerate 120w. So, two 50w 1156 replacement bulbs would work without burning down your vehicle.
I found the license plate frame to be the best choice for someone that doesn't want to ruin the lines of their vehicle. I've had reverse spot/fog lights bolted to hitches, bumpers, under frame..... and didn't care for going that route again. Upgraded bulbs is my 1st choice. If that doesn't work, something somewhat hidden, like the license plate frame, is a great choice. And, if you have a hitch, plenty of 'hitch lights' available too.
For a 1156, the JCwhitney back-up bulbs are a great choice. Autozone/advanceauto/napa/pepboys around here have equivalents:
http://www.jcwhitney.com/back-up-bulb-50-watt/p2003659.jcwx?filterid=j1#