I would have serious doubts that bitstamp even runs one single full node of their own ... probably outsourced.
you *seriously* beleive that a major bitcoin exchange does not operate thier own node? Something that can be achieved for <$100 with a standalone device and uses <64GB of storage?
get real. you can buy a 1TB harddrive for $50 today and store BIP101-enabled blockchain onto it for years to come. then pay $50 more for a 4TB drive to handle a few more years of growth. or are you still using the same computer you owned in 1999 with its 1.6GHz singlecore, 512MB ram, and 60GB HDD (all cutting edge)?
I know of several large bitcoin trading institutions that outsource btc operations to API providers ... or worse. It has nothing to do with hardware, they can't be bothered with the IT sysadmin overhead which for them is incomprehensible geek-speak, they are purely money-shufflers.