I remember being taught that граммов after numbers is rarely heard in speech (nearly everyone says грамм), but is preferred by some/many Russians in more formal writing.

So, John_Douglas, your memory of hearing people say "750 грамм изюм" (or whatever) in Russian markets is undoubtedly correct.

P.S. Russians may be interested to know that in 1954, the R.J. Reynolds tobacco company introduced a new brand of cigarettes -- Winston -- with the advertising slogan:

"Winston tastes good, like a cigarette should."

And at the time -- as recently as the 1950s -- it was considered quite безграмотный to use like in this fashion as a conjuction. Instead, formal grammar rules insisted on "Winston tastes good, as a cigarette should." There was quite a controversy about it, and the controversy grew when some American dictionaries began to approve this usage as "normal in colloquial speech," which outraged many schoolteachers, journalists, and editors.

Nowadays, the use of "like" in the Winston slogan sounds completely grammatical and causes no outrage -- in fact, it seems much more outrageous that these cigarettes were once advertised on TV cartoons for children!