I'm primarily a bassist, and as such am not well-acquainted with all of the neat gadgets and gizmos that guitarists more regularly interact with. Recently, I've began working on a folk/black/doom album, and have been incorporating the bowed upright bass where I can. I've found that the arco sound is ultra-fantabulous running through the intelligent harmony mode on the Boss PS-5. I can really get some great orchestral, cello-like melodies. However, the tracking on the PS-5 is unreliable to say the least, especially in the lower registers. When it works, it sounds great, but I can't depend on it in a live setting. So now I'm on the hunt for a harmonist that can track low and with reasonably thick vibrato. I know there's probably not anything perfect out there, but I'd really appreciate it if you guys could give some insight into your experiences with different stompboxes.

I've been looking at the following units:

1) DigiTech HM2 HarmonyMan (I was impressed with a demo video)

2) Boss PS-6 (I don't know just how much of an improvement it is over the PS-5, though)

3) Eventide Pitchfactor (this seems to be the most highly regarded on the web, but I'm not sure it's worth the extra money)

I would also probably use it for playing leads on guitar. Thanks in advance for any advice.