Sigma contemporary 100-400mm Bazooka lens

I don't know whether any member has bought this new lens and their views on it. I am thinking of buying this lens in place of my Canon 70-300mmf4 L lens, although I love the latter; more so the Canon keeps it's value very well. I note that with a crop body and 1.4tc it gives a "reach" of 896mm at the top end as against the Canon which goes up to 672mm at the top end. The weight of this Sigma is quite OK with me.

Many thanks

Nat