My 10wt experiences were full of pain and anguish at the end of the day, but I was able to throw 5/0 streamers, I won't say ease...I don't think anything with a "fast" 10wt is easy.
Then again, as the guy I hired to boat me around the estuaries of Cape May nicely remarked, I cast like a trout fisherman. I took it as a compliment. ;-)
I'm sure a 10wt rod could throw a reasonably sized double 6/0 streamer, as long as you didn't include a pound of lead and sopping wet bunny hair.
I did not use an Echo rod, however.