this is a list of current issues with heavy supported objects, that made me loose a couple of hours :-)
some "obvious" ones (the heavy compiler spits errors and warnings out)
-delread~ always needs an initial delaytime set, unlike in vanilla pd. actually, you cannot change delread~ delay time at runtime at all. use vd~in that case.
objects that do not work "properly":
-potentially all midi input. if you use more then one midi port in puredata the additional ports will have midi channel 1-16 remapped to portnumber*midichannel.
i.e. midi channel 1 on the second port will be channel 17 and so on. very useful feature to separate midi streams.
in heavy those additional ports will simply use the same midi channels as the default port. channel 1 stays channel 1. this is of course not desired, since it disallows any further routing of different ports.
-rpole~ does not work at all? at least i could not pass a signal through it in an abstraction, the abstractions simply did not output anything. EDIT: you have to feed a signal to the right inlet of rpole~ and you cannot use sig~ for that for some reason. use a line~ object as a workaround.