I personally don't believe anyone who says they have a 1520 without having ever experienced the sensitivity issue. I'm not saying people are lying, although invariably some will, but the fact is that a lot of people are used to similar effects coming from older Android devices, others simply don't use their phone enough for them to really notice (there are people here which have their 1520s last several, as in more than two, on a single charge for instance).
I happen to own two of these devices, one is an early Hong Kong unit, the other a later development handset. Both of these have the sensitivity issue, and it's as good or bad on both - simply meaning I can go an hour without noticing it, or I can go over a week. There's no real method to the madness, some days they just work, others they don't.
In the end though, the issue isn't bad enough that I'll consider returning it/them. There's no alternative to the 1520s at this point in time. Have you first gotten used to the size there's no going back.