bumping a HDD or RAM on a shiny new MacBook Pro is nothing that a decent soldering iron and top-grade solder can't help you accomplish
How exactly is a soldering iron going to help you upgrade the RAM?
On the non-retina MBP, it's in a normal SO-DIMM socket. Don't need anything besides a screwdriver.
On the retina MBP, it's going to be all BGA chips, and no iron, no matter how decent, is going to help you there.