I've seen several posts talking about the Synergy and the Iron Mace bows. The consensus seems to be that performance will probably be identical with the nod going to the Iron Mace because of the roller guard instead of the standard cable slide. How does the roller guard make the draw cycle any smoother?

Not sure this pertains to the roller guard design- but anytime I replaced my stock factory slide with a alpine "slide guide" or a sunders "fast slide"
I could notice a smoother draw.
Problem was the Saunders would pull my cable over too far and the slide glide would eventually stretch out. So I forced to go back to the factory slide.

Somebody mentioned HCA was selling their roller guards for other bows; I searched their website but didn't see any for sell.

If they were it would be interesting to add one to my current bows. I bet it would draw smoother with a roller than string on plastic friction.

Don't forget about the windstalker--it was supposed to be better than the stock slides and help in adjusting clearance issues.