I've had Zeiss 10x40 T*P* and Leitz 8x20 and currently have Leica 7x42 Trinovid, 8x42 Trinovid and, for my son, Leica 7x42 Ultravid HD. And Leica 10x25. I have tried them side by side in daylight against 8x32 or various makes. My opinion is that whilst there isn't much benefit that 10x40 offer over 7x42 (or 8x42) indeed a lesser field of vision and depth of field is the "price" of 10x40 they are all much much better than any "x30" currently available.
Personally I think that the "x30" are neither as good as "x42" nor as handy as the "x25" or "x20" (and "x20" is just impractical) that are out there. I think they are a niche and for me won't do what I want. So a waste of money as not practical enough whilst at the same time not handy enough.
Sorry it's not positive but that's my 2p worth.