I'd go for a compromise where, if the download is larger than say 1 megabyte, then the download goes to a temp file and is loaded back into &binvar when complete. You decide when realloc() becomes too clumsy and slow -- 1 mb? 32 mb?

&binvar is going to be most handy for people performing page scraping, where the html/xml they're scraping never even approaches 1 mb in size.

Well. At least I won lunch.
Good philosophy, see good in bad, I like!