Joebus500: Does upgrading your putter really help.
If you learn it it will. You don't buy putts with a new putter, though, just a tool to make better putts. Whatever you decide to do will be worthless unless you commit to learning the putter.
More precision and balance is always going to help but not if you don't give yourself time to learn how it plays. This means many rounds over many days. That doesn't happen in a free rental weekend, either. GL
p.s., That Rossa is a tremendously popular putter with a lot of long time players and for good reason-it works. :-)