You are right about the fact that it's difficult to get a flat response with that kind of crossover. On the other hand, placement is the key to balanced sound. Both FR and ST are very directive and output drops quite a bit off-axis (almost 20DB @ 30 deg. @ 20 kHz for the ST), so with proper placement (or misplacement), it's still possible to get great sound without using resistors and/or radical Xover slopes. I mean, with the ST sitting on top, it's possible to have a slight toe-in for the ST and no toe-in for the FR driver.