Castle have got the 1800KV motor - and they're thinking about doing a combo with it:
clicky
Another thing to bear in mind is that the Tekin does not come with a PC link - must be bought seperately for about $30. The Hobbywing doesn't either but has a programming card. The Tekin's programming (without PC) is very easy though, so it's not too bad.
Tekin's warranty is only 4 months (120 days), compared with the year that Castle offers. Tekin's CS was fine with me, though I shouldn't have to be writing to them multiple times. They are happy to send replacement parts to you though - Castle, less so.
Hobbywing would be an unknown quantity as for repairs - I guess it won't be too good.