I would say that there are a few similarities, but I wouldn't say that there are THAT many. I think that Royal Hunt might appeal to a lot of fans of DT and SX, though. I'm personally a big fan of all three.
Paradox is probably a good recommendation. To me, it's a classic.
But anything from Moving Target and after is great. Their first two (Land of Broken Hearts and Clown in the Mirror) have some great songs on them, but the vocals are a bit weak and lack some control, getting slightly off key sometimes. Moving Target and Paradox have D.C. Cooper (current Silent Force vocalist) on vocals, and Fear, The Mission, and Eyewitness have John West (Artension) on vocals. The later releases are more progressive than the earlier releases, for the most part. Eyewitness is similar to DT's Scenes from a Memory in some ways, and even has a needle being dragged across a record. (It's not a copy of Scenes, though. Just a similar approach.)
Don't expect the same level of technical virtuosity as SX and DT, but they aren't putzes either.
