Hi mrgold, like yourself I'm pretty new to prospecting and just recently bought a 2nd detector for the gold fields.
Both my machines are capable of finding gold in the right conditions, one is a Whites MXT Pro (VLF) and the other is a Whites TDI SL (PI), I usually try and detect a park at least once a week to keep learning about my detector and what it can do, I had a detect in a gold producing location last weekend but didn't find gold. I spend hours every week researching & reading as much as I can so when I get the chance to get out I'm hopefully better educated that the previous outing and hopefully some day soon I'll get lucky and find a piece of gold, but I know it aint that simple, if it was we'd all be rich or gold wouldn't be worth that much.
I think the key is to really know your detector and it's capabilities, if you want to find gold then the more you can research an area, your current detector or a detector that might suit your situation then the better off you'll be.
Asking which detector to upgrade to is like asking what's everyone's favourite colour, you're going to get a lot of different responses.
Maybe giving the general location of the area you plan on detecting?
Weight factor of the detector? I require light weight which is why I chose my 2 detectors and the coils to match.
How often you'll get out detecting?
Price range and accessories available for a particular model.
These are just some of the factors that will determine the best detector for your situation and online Internet research is the best way of narrowing down to 2-3 detectors that may suit, then ask peoples opinion on these you've narrowed down.
I might only be new to detecting but I've found it so rewarding researching as much as I could, it gives you a better understanding of "why" and makes every outing more rewarding and hopefully leading to finding my first nugget sooner rather than later.
The more research you put in the more you'll get out of detecting in the long run and the more others will guide you along the way.
Good luck with it and remember to keep it fun.