I love my palermo GM! I don't have the neverfull GM to compare though. I like the Palermo's zip top and adjustable shoulder straps. I did buy an alternate preloved Keepall strap because the shoulder strap on the palermo is too short and thin for my comfort. I don't find it too bulky.
I have both and they are both great bags. I do like the versatility of the Palermo Gm. I can wear her shoulder ( with both straps), crossbody, or arm. I also like the fact that it has a a zipper closure. The neverfull is functional and lightweight for the size of the bag. Both are great for travel but I also use my GM's for everyday too. Since the Palermo is retired then I would suggest trying this bag if you found one for a good price in the condition you want. If you don't like it then sell it. Neverfull will always be there when you are ready to buy.
i had both and ended up selling off the Palermo GM cos of the short shoulder straps (i need to get it on my shoulder with one hand while carrying my 14mths baby). Then I gave one Neverfull GM to my sister since I have 2 (mono and DE).