Appian cards are popular among traders for several reasons:
1. History of good reliability: Appian was doing multi-monitor cards before matrox or practically any other company even considered it. They've been serving the financial community for years and continually test their products on the latest trading platforms to ensure compatibility.
2. Quality Engineering: In the case of the G400 and G450, Matrox cards have a 300 or 360 Mhz RAMDAC on the first channel but only a 135 or 230 Mhz RAMDAC on the second channel. That means the second monitor can't be driven to the same level of performance as the first one can.
Why would they do this, you ask? Well, their cards were not designed to be dual monitor products from the beginning, so instead of making a new card from the ground up, they simply added a second channel with inexpensive components to accomodate an additional display. That's why Matrox uses lines like "DualHead functionality is integrated into every board."
Appian's dual monitor cards are engineered from the ground up to be multi-monitor products. They have dual 330 Mhz RAMDACs to ensure optimal performance on both monitors.
3. Patented Software: Appian's multi-monitor software, called Hydravision, contains numerous patented technologies that really give it an edge over their competitors. If you talk to anyone who has used both Appian and Matrox cards, they'll tell you that Matrox's software isn't even close to Appian's Hydravision.
4. Tech Support: Dual monitor video cards are 5% of Matrox's business, so don't expect the specialized tech support that you would get from a company who's entire business is manufacturing multi-monitor cards.