I recently played a game where the +X in HP+X was just harem. I opened silver-silver, and didn't bother getting the harem until WAY into the game. I'm now not really convinced you even need the +X if you get enough hunting parties. I mean, if you have silver gold estate copper HP, well, you are going to draw an extra card for every HP in your deck, and that will assuredly be enough to buy a province, just by random coppers (and maybe a silver).
I mean, if you have something spicy like militia or baron, or possibly even something OK like chancellor, go for it, but I think with navigator, or with counting house without extra buys, I'd just play money + HP.