Dave,
Was that a typo or were you actually referring to Hal 5? If so, version 5 did not use the Table format that Hal 6 uses and a lot of the Hal 5 based (3rd party) plugins simply will not work, ie, they are not interchangeable.
In either case, it would be nice if those plugins were tested on both 5 & 6, then separated according to which worked with which or didn't, as the case might be.