Keep or sell my Tamron?

I recently bought the Z6iii and have been loving it. I got with it the 24-120 f4 and I’m amazed by how sharp it is. I also bought the ftz ii adapter to adapt my old f-mount glass. One question I have is whether I should keep my Tamron 24-70 f2.8 G2 (f mount) or sell it for maybe 600 and put it towards another new z mount lens. Is the added speed really worth it? It's a great lens but I'm not sure how much I'd use it now that I have the 24-120. Thanks for your input!