My best friend worked at Heritage for quite some time, so I have a bit of "insider information". I have purchased a boatload of coins at Heritage over the last twenty years, but have been much more careful in recent years because I'm a little unsure as to their current policies in bidding on their own coins. (I mean, their practical policies, not what's stated in the "small print".)
I have also sold some through Heritage, but my last consignment (a few years ago) was almost certainly my last. It was 100% unreserved, and I was quite dissatisfied with the net results.
But that's only my personal experience - I know many collectors who have been happy both directions.