I'm new to the hobby and just learnt that lens "sharpness" is a thing, but I have no idea how much difference the measurement makes to the end result. For example a lens with "P-MPix" of 5, vs 15 in this example.

I am currently using a Tamron 18-200mm F/3.5 which, according to this website (Tamron 18-200mm F/3.5-6.3 Di III VC Sony E - DXOMARK) performs poorly on sharpness. I have been really enjoying this lens though because I take it hiking and it's nice and light. However the similar Sony lens (Sony FE 24-240mm F3.5-6.3 OSS - DXOMARK) rates better on sharpness, but weighs 300g more (which for my hiking kit is not negligible).

Would I expect to see much difference between these two lenses at full zoom, and a bit of cropping? And I guess the subjective part; would the Sony lens be enough of an upgrade to be worth the cost, and weight budget when hiking and traveling?

Thanks for any thoughts, perspective, you can offer a noob.