We've got the Antares Systems Avox Articulator Evo plug-in and the full Evo bundle running on a few different Pro Tools HD systems at the studio where I work. We rarely have issues running anything on any of these systems, and I've only had a need to run one of these at a time anyway. I don't know exactly how well this would run on an LE system or something comparable, but for me it has always ran smoothly.
The Antares Systems Avox Articulator Evo is definitely one of the coolest talkboxes I've used out there as it takes a unique approach to this awesome effect. It's definitely not your typical talkbox as you have a lot of precise control that you won't find elsewhere. The best part is that the plug-in also sounds fantastic. It's got a really smooth sound to it that is capable of wearing a lot of different hats in the sense that it's a versatile plug-in. The Avox Evo Vocal Toolkit must all be considered in order to decide if you want this plug-in since it can only be purchased in this bundle, but if you're doing a lot of vocal world, it's definitely a bundle worth having.