From what I can make out, the GT610 is hardly an upgrade from the GT520 - when the 610 was launched, the comment was that it was no more than a rebadged 520. Perhaps you know different? Anyway, to your question: on graphics cards - like PCs - more memory is always good. But if you had the budget, I'd be looking at something with DDR5 memory rather than DDR3, as it's significantly faster.
Surface Pro (2017) vs Surface Pro 4