I'm just gonna post this vid.
http://www.youtube.com/watch?v=pwkML-WBQGg
You can see how frustrating forward exe.beasts are, and a trade is always gonna be in Test's favor.
I wouldn't say Test is Faust most difficult match. Chipp and Millia rank above him there. Problem is most of you haven't had the opportunity to play a decent Chipp, or even Millia. You don't get many FaustxChipp match vids from Japan either.
Its just very difficult to keep the correct distance from Testament to where you want to fight him. Too close you get forward beast, and long range you get far beast. At your best distance Testament can easily avoid your long range pokes, 5S, 2HS with backdashing.