Huh? I don't have any PDF files larger than 150 MB (2500+ pages long).

It won't be a problem. 512 MB is more than enough. The previous revision had 256 MB (that's a bit tight), and the newer PCB does not have RAM less than 1 GB.

Printing stack supports streaming, either per-band (part of a single page) or per-page. Even 1200 DPI CMYK color page is less than 50 MB.