Is it possible to find a really good items in arena compare to cata?
like for example 200ee+?, 50+dex/str XD

if so, what's the comparison between cata (not in group) finding good items.

thanks~

There isn't a comparison really... just think of it this way:

Full cata... chance of good item dropping is slim.... chance of getting that item = 20%... thus reducing your chance
Arena... chance of good item dropping is slim... chance of getting that item = 100%... thus improving your chance

The above is based on the fact that the location has a 0.002% chance to drop an item over 180EE / 40 Stat (based on level etc blah)

You have to decide... I basically join catas for the levels 85% of the time... and on the off chance... I may get a drop or two.
I go arena when there are hardly anyone on... then I can well items also...