well i'm not a american line fan at all but i'll try to describe it as objective as i humanly can lol Temperment: i never meat in eye or asked how the temperments of american lines but i do now well the italian lines. from what i saw so far they can be very friendly dogs to family and strangers if they were exposed from young age propaply, dogs that weren't trought this usually grew up to be very agressive, dominate dogs or very fearfull, much as any breed Working ability: never tested by myself an american line but i do have some friends that own such dogs. i did saw more titles dogs in US ( and i speak schh, IPO and herding titles ) than in other places. many of those US dogs usually had alot of italian blood in them or were imported from Italy and places like that. the male i have a female from ( Touno) did produced some great studs with schh titles and as much as schh can't tale to much about a dog it does say about the prey drive and wilingns to work. the same i saw from the father and granfather ( half brothers) of my bigger girls who also produced some CAL and schh dogs so as much as i saw from the italian line without knowing well the american lines i do say the italian ones have more work potantial ( sp) Size and Structure: now here remmber i'm not here to insulte anybody from any side so please take it easy as i saw the american line do have alot of size usually and good bodys, big and strong bones but, and here i have a strong BUT, the heads, the head is THE most important thing first seen in CC, i never so far saw a pure american line that had a good corect head, they always have heads to short and wied or way to long and pointy, sorry but this isn't a CC head at all. hope nobody offended to eatier side :) more to that from now any Italian ch must also own a CAL2, not to much of working title but it's alredy somthing