Let's see.
You have to spend basic xeons and lant to get the items to +10 which will then be the same as having a +0 item compared to a +30 item. Additionally the chances to get to +20 are lower than getting to +10 at the moment.
Nope, doesn't sound like a solution to me. Put them to +30 and leave all items on +30.
You are right. Then could move the current chances 10 plusses and make them go from +11 to +40 and leave it from +1 to +10 at 100% chance. But that wouldnt give them extra profit except for the initial one of people going from +30 to +40, but we know that if it doesnt give them profit they wont do it.