Always when I read about any efficient persistent data structures they use pointer computational model. I'm wondering if you know any efficient implementation which uses power of RAM model?
Paul F. Dietz's "Fully Persistent Arrays" uses a variant on van Emde Boas trees, which rely on arrays and also on integers being represented as words.
Brodal et al.'s "Fully Persistent B-Trees" relies on arrays.
Davoodi et al.'s "Cache-Oblivious Persistence" applies a persistence transform to data structures that don't necessarily work in the pointer model.
The Bentley-Saxe logarithmic method, also known as cache-oblivious lookahead arrays is naturally partially persistent, and relies on arrays for the insert time to be $o(\log_B n)$ in an external-memory setting.