A few things to discuss here...
1. if you are eligible for a 1yr upgrade, you can upgrade but you only get $75 off the FULL retail price of the phone.
2. if you use the other line's upgrade, wait AT LEAST 24 hours to switch it to your phone number.
3. cancellation fees are $200 from the 31st day of the signing of the new contract and pro-rate AFTER 6mos until they are a minimum of $50. if the phone is cancelled within 30 days of the upgrade, the upgrade will be reversed and if the phone is not returned to the store, in like new condition, in the box with all contents you will be charged the FULL retail price of the phone.
4. if you are trying to get moved to an earlier date for upgrade...transfer to account services. tell them a representative told you there was a supervisor in their department running a pilot program for early upgrades. It is usually only 2 weeks early at most. However, I have, in some cases, got them to make exceptions for customers who had broken phones and needed a phone asap because they have kids or whatever. if they did not get the upgrade they would switch to another carrier so that they could get a new phone that day. not saying try it, just saying it's been done before.
Best of luck to you. I know how bad you all want this phone. However, I prefer to wait and let the carrier get the first batch out of the way. When a phone is released pre-maturely it is more likely to have bugs (example: CL14 update to fix what was wrong with early released Moment and HTC sync update that was released to fix what was wrong with the Hero). I am not saying I anticipate anything being wrong with the EVO. I know it has been ready for release for quite some time. And corporate managers have had theirs for a while. I have yet to hear of any problems ... I'm just saying: Patience is a virtue and sometimes it pays off in the end.