I have a pair of HF5s and my much cheaper FX67s massively outscore them for bass. It's not that they produce more bass (I use a Cowon J3, so I have all the amp volume and EQ in the world) its just that the bass on the 67s is more musical, if that makes sense. In fact, the 67s are - to my ear, which is all I care about - almost as good as the HF5s in every department except those where they are better. Given that they're stupidly cheap on ebay and absolutely excel at base, I'd buy a pair and then see if I still felt the need for anything more expensive. (But then I'm saying that to everyone today - I love my 67s.) Search for Katun's review if you're interested.
Anyway, the HF5 has a great rep in general, but bass (and awful microphonics) are usually considered its weak points I believe.
Other suggestion: tell people more about the player you are using - the qualities of your amp and whether you have good EQ will make a difference to the IEMs you should use.
