The simlock of emobile's em-one has nothing to do with what you've written.
I think you missed the point.
Their business model is to make money from their network service (as should be clear
from their Y2000/month contract, I guess em-one is similar).
If you have a valid SIM in the slot then it's fine, it doesn't need to phone
home, you just have to get the SIM - they won't let you have one unless you can sign
the contract, they won't let you sign the contract unless you are resident in Japan.
I've spent a long time looking at the em-one and Willcom stuff in local stores and
although it would be nice to have the option, I still prefer my Z. Today I looked
at an N810, hands on, for the first time. If I had to ditch the Z I would get the
810.
I've also looked at the Kohjinsha (tacky) and Eee (better but still ugly). I still
much prefer the power:size ratio of a Z. The other 2 are too big if you mainly want
PIM and a little bit of coding.