Just from my little expirience with the Talon, I'd say it's simply not in the same league as the HP-CS or Infinity.
The Infinity is a nice brush. The needle and nozzle materials are a bit soft (which is why they are cheaper than Iwata parts), and require replacing pretty regularily. Also, the finish on H&S brushes are nickel plating, not chrome, so they are more prone to wear and more vulnerable to ammonia-based cleaners. The finish is purely cosmetic, though, and doesn't effect the performance of the airbrush.
With the .15 nozzle/needle in, the Infinity is a pretty impressive detail brush. I would say it's about as close to a micron as I've come across. But, it does seem to be a bit pickier about paint viscosity and more prone to clogs. So, the extra fine-line performance comes with some inconvinience. Fortunately, it's a very user-friendly designed brush that you can break down and clean well fairly easily.
IMO, if H&S put some extra money into using better materials for the needles and nozzles, and put in just a bit more for the finishing touches, it would be easily one of the "elite" airbrushes. Since they compromised to fit it to a price point, though, it comes up short of the best. Still very good, though.
The HP-CS is a true "jack of all trades" brush. Excellent control, good spray quality, and very suprising detail ability (especially from a .35 tip). Not to mention that they're built like tanks, very durable, and very reliable. It can handle paints of nearly any viscosity, and even small flakes and pearls. And it is precise enough to handle some very fine detail work (if you watch Craig Fraisers videos, he's usually using an HP-CS for everything but the very, very tiniest details). Where the HP-CS really shines is in those mid-range areas (fades, daggers, etc). The trigger action is just very linear and smooth.
As for which I'd recommend to buy, it depends on your intention. If you want a detail brush, the Infinity with a .15 or .2 tip will get you finer detail easier than an Eclipse. If it's going to be your only, or main, airbrush, I'd go with the HP-CS. As a do-it-all airbrush, it's very hard to beat. It puts most of the "2-in-1"s or "3-in-1"s to shame, and does it with a single nozzle and needle. But, I doubt you'd regret buying either one.
For what it's worth, I use my HP-CS quite a bit more than I use my Infinity...