32Gb or 64Gb?

I have been holding off buying a new 17" Dell XPS 9700 which is specced to accommodate 64Gb ram but only available in the UK with 32Gb fitted by the factory.  I can fit two 32Gb modules in the new laptop but would prefer not to run the risk of pilot error with the torx screwdriver.  I have in fact just retrofitted 64Gb in my xps 15 7590 and it seems to be working well.

I mainly paint in Photoshop and use the Mixer and Art History brushes a lot.  I have found that since adding 32Gb more (now total 64Gb) to my laptop the Mixer brush does not get bogged down so often.  But is the brush's performance dependant on the memory available or the heft of the processor?  Does the video card matter? I don't feel a need for a more advance card. I have a GTX 1650 currently.

The cpu now is an OctalCore Intel Core i9-9980HK, 4400 MHz.  The cpu in a 9700 would be Up to 10th Generation Intel® Core™ i7-10750H . Does the newer cpu bring benefits I will notice.

I am keen to have the larger screen so hope to move to XPS 17 idc - a laptop is the only arrangement that works for my circumstances so a desktop pc is a no go.

I'd be grateful for any advice on whether more ram and a more powerful cpu will be a benefit.  Will I notice the difference?

Thanks