First off ... try a nice meatball recipe for the burgers - it works nice! Remember that a 70/30 ground beef is better for burgers than a 80/20 - it's just like steak - less fat = less flavor!
There are so many choices - what people don't understand is that Italian food is just that - FOOD! ... with a little touch of love.
In my opinion Panchetta is misunderstood like Prosciutto.
I would personally prefer to wrap the burger in Prosciutto
which is ALWAYS sliced wafer thin - you hold it to the light
if you don't see light through it - that's way too thick!
As for your idea of Smoked Gouda ... you do know it's liquid smoke on there - no? Cheese melt's in heat :)
Personally; I love Fontina (especially the Danish)
Other great cheese for this type of burger would be a well aged Provolone - the longer it is aged - the more full body flavor you get.
If you prefer something less powerful my suggestion would be a Kasseri or even kashkaval. Those are more difficult to slice.
Also - try adding about 1 tablespoon per burger of Reggiano Parmigiano (Shredded better than grated because it carries the taste more)
Also - try nice medium fine chopped Portobello mushroom in the meat mix or grilled slices with a generous wetting down of Olive Oil to wet it for the fire - it's a more full flavored mushroom so it will carry through the flavor and not be lost.
Also - add about 1/2 can (for 6 to 8 burger) of tomato paste in the mix ...
and don't forget the Parsley - Food with lottsa Garlic should be loved by Parsley - Parsley helps fix garlic and onion breath ... it's the chlorophyll that helps (just like the old gum called Clorets)
Now for toppings - a nice meaty tomato - not too juicy - personally I love the Roma tomato sliced long way and dusted with Oregano, salt, and pepper, and soaked in Extra Virgin Olive Oil (the greener the oil the more flavor it holds) and a splash of Chianti over the tomato.
this post could go on and on .... however - Ciao For Now!
(For the insight - I was teaching women in their 30's and 40's how to cook Italian with love when I was in my teen's - and now am in my lower 50's - also - first birth of the first Generation born in the USA of Italian last name)