By the way, i wasnt trying to dissuade you from going 100, just offering up the main differences.
I cant say anything more than i got from playing that one game, as it's all i've done at 100, but he's only ilvl 701 and did just fine with no artifact and non-BiS. I wouldnt worry about anything else too much... ret paladin is quite strong. I am not "good" at ret and did fine in that particular BG, anyway. The 2 deaths were just due to us 5 capping the horde back to spawn and me getting slammed there (twice) trying to hold farm with only 3:
http://imgur.com/57K2Aai
Get your artifact if/when you can tho, the difference should be quite noticeable.