i didn't think there was THAT much difference.
:Q
anyway, it is always a good idea to pick up the [higher end] video card with more vRAM ... it also helps when you sell the card* and in each case the higher vRAM version showed its strengths as it neared the end of it's useful life in my rig.
... so, it Worked in every case for me ... Rage Fury32 [way faster than the 16MB ver], Radeon 64 DDR, R8500/128MB [1-3% faster], 9800xt/256 [5-10+% faster than 128MB 9800p] and x850xt ... why mess with a 'trend'?
*the person you sell the card to is likely not as 'technical' as you and is willing to pay a premium for the "ultimate 512MB version" ... so the "extra" i paid was usually recouped.
[i wish my x850xt has 512MB vRAM --right now]