You´ve probably seen this review/comparison:
http://www.birdforum.net/showthread.php?t=38202
I think there was also an archived one on CN, also by Henry.
I´ve never had SE 10x42, but I´ve had SE 8x32 and currently have EII 10x35 plus 8x30. I personally prefer the EII for the wider and easier view, but the SE for handling. It´s just a nicer shape to hold, and rubber-armoured. Focusser, etc. seems exactly the same. Flatter field in the SE´s, but wider in the EII´s and I see about the same amount of "sharp" field in both the 8x versions. I think the EII 10x35 would complement your 8x32 SE nicely, but maybe check out a 10x42 SE just in case?