Yep, Parhelia works well with LFS - it is a proper DX8 card... but isn't as fast as more modern cards and you can't turn up the resolution too high.
The problem is, that ATI (definitely - they told me) and nVidia (probably - i guess) believe that there is no customer demand for triple head cards. So they just make these dual head cards.
Dual head is absolutely pointless for racing games, or any game in first person. I think that triple head cards would sell, to people who will make that extra effort to find some old CRT monitors, second hand at a good price, or actually spend the money to buy new ones...
But it's no good me saying that, please write emails to nVidia and ATI and ask them when / if they will make a triple head card, and explain to them why it's so much more useful than a dual head!
It can work as dual head anyway if someone only has two monitors... so they've got nothing to lose!
No harm in writing to Matrox to ask them to make a nice new DX9 super fast triple head as well.