The 320 is better. It does more with less in the way of signals. I wouldn't say if you already had a 220 to sell it and go buy a 320. But starting from nothing, I'd definately recommend a 320 and I'd recommend DU hound supply(the owner of this site). Not for any reason other than he has great customer service and prices.
Don't buy the hype.
"Those who hammer their guns into plows, will plow for those who do not." - Thomas Jefferson