IMHO, the Starter putter is the best club in that set. The only flaw that I remember is on the "balance" side: It strays quite a lot on long putts. I've used mine as long as I was comfortable with it, about L55.
Before buying a custom putter, you should know which is favourable for you as a "ding" or "off ding" putter.
You might want to wait for the next free rental days...