[rhn_mk1]

It depends on how you define "serious". If it works for 99% people with a net positive and it doesn't work at all for 1%, is it serious enough to keep the old version?

My experience says that it will get steamrolled and the 1% left hanging, looking at significantly worse solutions, or none altogether.

[otterley]

A 1% failure rate would be huge. That's 1 out of every 100 customers. No rational carrier would tolerate that.

I know we all hate telcos and mobile phone carriers -- and a lot of their mistrust is quite frankly deserved -- but this seems like an edge case that most customers won't even run into. First they need to switch devices, which eliminates most customers, and then second, they need to experience some kind of failure on switch. If the failure rate is any higher than before, I would be surprised. But let's wait to see the data before we all go up in arms.